Keywords
Key points
- •The range of presentation with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, from asymptomatic infection to critical illness, changes with age. Older adults will more commonly have an atypical clinical presentation, nonspecific symptoms, and blunted fever response to SARS-CoV-2 infection.
- •Most coronavirus disease 2019 (COVID-19) hospitalization and mortality occur in older adults, with severity compounded by underlying illnesses.
- •Although vaccination significantly reduces the risk of severe COVID-19 and mortality in older adults, it may take 3 or more exposures for the spike protein as antigen to develop an antibody repertoire that can neutralize a broader range of variants.
SARS-CoV-2 | Severe Acute Respiratory Syndrome Coronavirus 2 |
ICU | Intensive Care Unit |
CDC | Centers for Disease Control and Prevention |
WHO | World Health Organization |
CLIA | Clinical Laboratory Improvement Amendments |
PPE | Personal Protective Equipment |
PASC | Post-Acute Sequelae of COVID |
COPD | Chronic Obstructive Pulmonary Disease |
Introduction
History/Background


Definitions
Centers for Disease Control and Prevention and World Health Organization definitions of coronavirus disease 2019 stages
Acute coronavirus disease 2019
Term | Definition | |
---|---|---|
SARS-CoV-2 | Severe acute respiratory syndrome coronavirus-2SARS-CoV-2 named by the International Committee on Virus Taxonomy is the virus that causes COVID-19 3 | |
COVID-19 | Coronavirus disease 2019 is an infectious disease, designated by WHO as COVID-19, which is caused by SARS-CoV-2, a coronavirus discovered in 2019 4 | |
Asymptomatic infection | Infection while having no symptoms. Includes both presymptomatic individuals and individuals who will never develop symptoms | |
Presymptomatic infection | Infection before inevitable development of symptoms | |
Transmission 144
Presymptomatic, asymptomatic and post-symptomatic transmission of SARS-CoV-2: joint British Infection Association (BIA), Healthcare Infection Society (HIS), Infection Prevention Society (IPS) and Royal College of Pathologists (RCPath) guidance. BMC Infect Dis. 2022; 22: 453 | Presymptomatic | An index has no symptoms during the exposure period of their closed contacts but later develops symptoms |
Asymptomatic | An index case never develops symptoms or signs of infection | |
Postsymptomatic | An index case has no symptoms during the exposure period of their close contacts, but previously had symptoms | |
Criteria of suspected cases of SARS-CoV-2 infection, 145 When suspicious: new onset fever and/or respiratory symptoms (eg, sore throat, cough, nasal congestion, rhinorrhea, shortness of breath). Other common nonrespiratory symptoms: new changes in taste or smell, diarrhea, chills, anorexia, headache, and muscle pain | Clinical criteria Epidemiologic criteria | Acute onset of fever and cough OR Acute onset of any 3 or more of the following signs or symptoms: fever, cough, general weakness/fatigue, headache, myalgia, sore throat, coryza, dyspnea, nausea, diarrhea, and anorexia Contact of a probable or confirmed case or linked to a COVID-19 cluster |
Illness | Severe acute respiratory illness | |
Testing | No clinical signs or symptoms, nor meeting epidemiologic criteria, with a positive professional use or self-test SARS-CoV-2 antigen-RDT | |
Clinical criteria in the absence of a more likely diagnosis (CDC) 146 (Organ systems and associated symptoms and signs by all ages and older adults are summarized in Fig. 3. As discussed later in this article, older adults may present differently.) | Acute onset or worsening of at least 2 symptoms or signs | Fever (measured or subjective), chills, rigors, myalgia, headache, sore throat, nausea or vomiting, diarrhea, fatigue, congestion, and runny nose |
OR | ||
Acute onset or worsening of at least one symptoms or sign | Cough; shortness of breath; difficulty breathing; olfactory disorder; taste disorder; confusion or change in mental status; persistent pain or pressure in the chest; pale, gray, or blue-colored skin, lips, or nail beds, depending on skin tone; inability to wake or stay awake | |
OR | ||
Severe respiratory illness with at least | Clinical or radiographic evidence of pneumonia, or acute respiratory distress syndrome | |
Laboratory criteria (CDC) 146 ,Laboratory evidence using methods approved or authorized by the US Food and Drug Administration (FDA) or designated authority | Confirmatory laboratory evidence | Detection of SARS-CoV-2 ribonucleic acid (RNA) in a postmortem respiratory swab or clinical specimen using a diagnostic molecular amplification test performed by a Clinical Laboratory Improvement Amendments (CLIA)-certified provider OR Detection of SARS-CoV-2 by genomic sequencing |
Presumptive laboratory evidence | Detection of SARS-CoV-2–specific antigen in a postmortem obtained respiratory swab or clinical specimen using a diagnostic test performed by a CLIA-certified provider | |
Supportive laboratory evidence | Detection of antibody in serum, plasma, or whole blood specific to natural infection with SARS-CoV-2 (antibody to nucleocapsid protein) OR | |
Detection of SARS-CoV-2–specific antigen by immunocytochemistry in an autopsy specimen OR | ||
Detection of SARS-CoV-2 RNA or specific antigen using a test performed without CLIA oversight | ||
Epidemiologic linkage 146 | One or both of the following exposures in the prior 14 d (CDC) | Close contact a with a confirmed or probable case of COVID-19 diseaseClose contact is generally defined as being within 6 feet for a cumulative period of at least 15 min during a 24-h period. However, this depends on several exposure and setting variables (eg, in the setting of an aerosol-generating procedure in a health-care setting without proper PPE, it may be “any period of time.” OR |
Member of an exposed risk cohort as defined by public health authorities during an outbreak or high transmission | ||
Probable case (WHO) 145 | An individual who meets clinical criteria of suspected case and is a contact of a probable or confirmed case, or is linked to a COVID-19 cluster | |
Confirmed case (WHO) 145 | An individual with a positive nucleic acid amplification test (NAAT), regardless of clinical criteria or epidemiologic criteria OR A person meeting clinical criteria and/or epidemiologic criteria with a positive professional use or self-test SARS-CoV-2 antigen-RDT | |
Symptomatic case (WHO) 145 | An individual who is infected with SARS-CoV-2 and has symptoms | |
Case classification (CDC) 146 | Suspect | Meets supportive laboratory evidence with no prior history of being a confirmed or probable case |
Probable | Meets clinical criteria and epidemiologic linkage with no confirmatory or presumptive laboratory evidence for SARS-CoV-2 OR | |
Meets presumptive laboratory evidence OR | ||
Meets vital records criteria with no confirmatory laboratory evidence for SARS-CoV-2 | ||
Confirmed | Meets confirmatory laboratory evidence | |
Testing | Positive test | A positive test indicates likelihood of present or past SARS-CoV-2 infection whether symptomatic or recovered |
Types of tests 148 , 149 , 150 , 151 | Direct detection of SARS-CoV-2 RNA by NAATs or reverse-transcription polymerase chain reaction from the upper respiratory tract) | |
Serologic tests detecting antibodies to the virus in the blood. Usually used to detect previous infection or response to vaccine | ||
Antigen tests detecting SARS-CoV-2 antigen with nasal swab or saliva sample | ||
Breathalyzer that uses gas chromatography-mass spectrometry to detect exhaled volatile organic compounds specific to SARS-CoV-2 infection | ||
Interferon-gamma release assay | ||
Definition of COVID stages (CDC and WHO) 18 ,19 | Acute COVID-19 | Symptoms of COVID-19, up to 4 wk following the onset of illness |
Long COVID or Post-COVID Conditions (PCC) | (See text for details) (Also called long-haul COVID, postacute COVID-19, postacute sequelae of SARS CoV-2 infection (PASC), long-term effects of COVID, chronic COVID) 23 |

Long COVID or postcoronavirus disease 2019 conditions
Epidemiology
Risk for Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Older Adults
Immunosenescence and immunity in older adults with coronavirus disease 2019
Vaccination in older adults with coronavirus disease 2019


Aging (affecting clearing of virus)
Hearing and visual changes with age
Multiple Morbidities (Affecting Immune Competence, Clearance of Virus)
- •Cancer
- •Cerebrovascular diseases
- •Chronic kidney disease
- •Chronic lung diseases (including COPD, interstitial lung diseases, bronchiectasis, pulmonary embolism, and pulmonary hypertension)
- •Chronic liver diseases (including cirrhosis, alcoholic hepatitis, alcoholic liver disease, and nonalcoholic fatty liver disease)
- •Type-2 diabetes mellitus
- •Disabilities
- •Congestive heart failure, coronary artery disease, and other cardiomyopathies
- •Dementia
- •Obesity (body mass index [BMI] ≥30 kg/m2)
- •Physical inactivity
- •Smoking history
- •Use of immunosuppressive medications including steroids
Exposure and Transmissibility
Reinfection and Breakthrough Infection in Older Adults
Clinical Characteristics of Coronavirus Disease 2019 in Older Adults

Coronavirus disease 2019 complications
Severity of coronavirus disease 2019
Coronavirus disease 2019 in older adults: risk stratification, risk factors, and prevention
Atypical clinical presentation of coronavirus disease 2019 in older adults
Long COVID or postacute sequelae of coronavirus disease 2019 older adults
Future directions
- •COVID-19 vaccine frequency and acceptance to optimize immunologic response and clinical effectiveness need further studies that emphasize outcomes in older adults.
- •The refinement of definitions for PASC, its epidemiology, impact, and approaches to management will evolve as new data become available.
- •We need to better understand what drives the severity of SARS-CoV-2 infection in older adults, especially because it relates to frailty, immune senescence, and inflammation.
Clinics care points
- •Older adults with COVID-19 have higher hospitalization and case fatality rates than younger adults.132
- •SARS-CoV-2 infection remains asymptomatic from 33% to 90% of older adults, depending on underlying immune status from prior infection, vaccination, and circulating strain.133
- •The high frequency of asymptomatic SARS-CoV-2 infection makes symptom-based testing ineffective as a sole means for early outbreak detection of SARS-CoV-2 in NH populations.113
- •Fever response is blunted in older adults with COVID-19; setting a lower threshold for triggering SARS-CoV-2 testing in older adults in NH settings improves sensitivity and can alert staff to consider the need to test for SARS-CoV-2 days earlier.104,105
- •Older adults with underlying morbidities disproportionately suffer the most severe COVID-19 outcomes.134,135
- •Health-care providers should consider adding COVID-19 to the differential diagnosis of clinical presentations such as falls, confusion, delirium, and worsening of functional impairment. This should drive SARS-CoV-2 testing, treatment, and measures to reduce spread (eg, distancing, masking, isolation).116
- •Older adults more often experience any of a broad range of sequelae of respiratory failure, fatigue, hypertension, memory problems, kidney injury, mental health problems, hypercoagulopathy, cardiac dysrhythmias, deep vein thrombosis, pulmonary embolism, and bleeding after COVID-19.108,109
- •In older adults, vaccination reduces SARS-CoV-2 incident infection and subsequent severity,134,135effects bolstered by booster vaccines.52
- •N-95 respirators provide superior protection to other masks and can protect users from getting infection when caring for or visiting those infected with SARS-CoV-2.114In conjunction with social distancing, minimizing time in rooms with infected individuals, frequent hand washing, and proper use of other PPE, individuals can avoid becoming infected. Absent N-95 respirator availability, other masks still can offer some protection. The use of masks should follow the greater standard of personal preference of health department guidelines.
Disclosure
Acknowledgment
References
- What we're reading: roots of chinese illness discovered.(Available at:) (Accessed on July 20, 2022)
- A timeline of COVID-19 developments in 2020.(Available at:) (Accessed on July 20, 2022)
- The species Severe acute respiratory syndrome-related coronavirus: classifying 2019-nCoV and naming it SARS-CoV-2.Nat Microbiol. 2020; 5: 536-544
- WHO Director-General's remarks at the media briefing on 2019-nCoV on 11 February 2020.(Available at:) (Accessed on July 20, 2022)
- First travel-related case of 2019 novel coronavirus detected in United States.(Available at:) (Accessed on July 20, 2022)
- Bats are natural reservoirs of SARS-like coronaviruses.Science. 2005; 310: 676-679
- Structural basis of receptor recognition by SARS-CoV-2.Nature. 2020; 581: 221-224
- A pneumonia outbreak associated with a new coronavirus of probable bat origin.Nature. 2020; 579: 270-273
- Monitoring Variant Proportions.(Available at:) (Accessed on October 29, 2022)
- New SARS-CoV-2 Variant of Concern Identified: Omicron (B.1.1.529) Variant.(Available at:) (Accessed on July 24, 2022)
- Emergence of SARS-CoV-2 Omicron lineages BA.4 and BA.5 in South Africa.Nat Med. 2022; 28: 1785-1790
- Increased risk of SARS-CoV-2 reinfection associated with emergence of Omicron in South Africa.Science. 2022; 376: eabn4947
- Available at:) (Accessed on July 20, 2022) (
- Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China.Jama. 2020; 323: 1061-1069
- Severe Outcomes Among Patients with Coronavirus Disease 2019 (COVID-19) - United States, February 12-March 16, 2020.MMWR Morb Mortal Wkly Rep. 2020; 69: 343-346
- COVID-19 weekly cases and deaths per 100,000 population by age, race/ethnicity, and sex.(Available at:) (Acessed October 22, 2022)
- COVID-19 Nursing Home Data.(Available at:) (Accessed July 7, 2022)
- A clinical case definition of post-COVID-19 condition by a Delphi consensus.Lancet Infect Dis. 2022; 22: e102-e107
- Post-COVID conditions: information for healthcare providers.(Available at:) (Accessed on July 28, 2022)
- Leading Causes of Death and Injury.(Available at:) (Accessed on July 29, 2022)
- Significant reduction in vaccine-induced antibody levels and neutralization activity among healthcare workers and nursing home residents 6 months following coronavirus disease 2019 BNT162b2 mRNA vaccination.Clin Infect Dis. 2021; 75: e884-e887
- Age-Dependent Neutralization of SARS-CoV-2 and P.1 Variant by Vaccine Immune Serum Samples.Jama. 2021; 326: 868-869
- Long COVID or Post-COVID Conditions.(Available at:) (Accessed on July 28, 2022)
- The immunologic theory of aging.Gerontologist. 1964; 4: 195-197
- Roy Walford and the immunologic theory of aging.Immun Ageing. 2005; 2: 7
Azar A, Ballas ZK. Immune function in older adults. In: UpToDate, Marsh R (Ed), UpToDate, Waltham, MA, Accessed on July 29, 2022.
- Influence of immune aging on vaccine responses.J Allergy Clin Immunol. 2020; 145: 1309-1321
- Comparative effectiveness of high-dose versus standard-dose influenza vaccination on numbers of US nursing home residents admitted to hospital: a cluster-randomised trial.Lancet Respir Med. 2017; 5: 738-746
- Diminished immune responses with aging predispose older adults to common and uncommon influenza complications.Cell Immunol. 2019; 345: 103992
- Reduced BNT162b2 messenger RNA vaccine response in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-naive nursing home residents.Clin Infect Dis. 2021; 73: 2112-2115
- Fever in the elderly.Clin Infect Dis. 2000; 31: 148-151
- Immunosenescence and COVID-19.Mech Ageing Dev. 2022; 204: 111672
- p53 and Cellular Senescence.in: Masoro E A.S. Handbook of the biology of aging. Academic Press is an imprint of Elsevier, Burlington (MA)2006: 151-154
- Increased immunosuppression impairs tissue homeostasis with aging and age-related diseases.J Mol Med (Berl). 2021; 99: 1-20
- The impact of ageing on natural killer cell function and potential consequences for health in older adults.Ageing Res Rev. 2013; 12: 1069-1078
- Natural killer cells as an initial defense against pathogens.Curr Opin Immunol. 2006; 18: 391-398
- SARS-CoV-2 inhibits induction of the MHC class I pathway by targeting the STAT1-IRF1-NLRC5 axis.Nat Commun. 2021; 12: 6602
- Perforin, COVID-19 and a possible pathogenic auto-inflammatory feedback loop.Scand J Immunol. 2021; 94: e13102
- Functional exhaustion of antiviral lymphocytes in COVID-19 patients.Cell Mol Immunol. 2020; 17: 533-535
- Diversity and clonal selection in the human T-cell repertoire.Proc Natl Acad Sci U S A. 2014; 111: 13139-13144
- The influence of age on T cell generation and TCR diversity.J Immunol. 2005; 174: 7446-7452
- Thymic Aging May Be Associated with COVID-19 Pathophysiology in the Elderly.Cells. 2021; 10
- T-cell receptor repertoires as potential diagnostic markers for patients with COVID-19.Int J Infect Dis. 2021; 113: 308-317
- Decreased proliferative capability of CD4(+) cells of elderly people is associated with faster loss of activation-related antigens and accumulation of regulatory T cells.Exp Gerontol. 2004; 39: 587-595
- Antigen-specific adaptive immunity to SARS-CoV-2 in acute covid-19 and associations with age and disease severity.Cell. 2020; 183: 996-1012.e19
- COVID-19 Vaccines.Infect Dis Clin North Am. 2022; 36: 481-494
- Pfizer-BioNTech Fact Sheets (English) and FAQs.(Available at:) (Accessed on August 03, 2022)
- Spikevax and Moderna COVID-19 Vaccine.(Available at:) (Accessed on August 03, 2022)
- Emergency Use Authorization (EUA) of the Novavax COVID-19 vaccine, adjuvanted to prevent coronavirus disease 2019 (COVID-19).(Available at:) (Accessed on August 03, 2022)
- Emergency use authorization (EUA) of the Janssen COVID-19 vaccine to prevent coronavirus disease 2019 (COVID-19).(Available at:) (Accessed on August 03, 2022)
- Reduced Risk of Reinfection with SARS-CoV-2 After COVID-19 Vaccination - Kentucky, May-June 2021.MMWR Morb Mortal Wkly Rep. 2021; 70: 1081-1083
- Effectiveness of a Second COVID-19 Vaccine Booster Dose Against Infection, Hospitalization, or Death Among Nursing Home Residents - 19 States, March 29-July 25, 2022.MMWR Morb Mortal Wkly Rep. 2022; 71: 1235-1238
- Human in vitro nasal and tracheal ciliary beat frequencies: comparison of sampling sites, combined effect of medication, and demographic relationships.Ann Otol Rhinol Laryngol. 1991; 100: 378-384
- Oxidative stress associated with aging activates protein kinase Cε, leading to cilia slowing.Am J Physiol Lung Cell Mol Physiol. 2018; 315: L882-L890
- SARS-CoV-2 infection induces the dedifferentiation of multiciliated cells and impairs mucociliary clearance.Nat Commun. 2021; 12: 4354
- Outcomes of respiratory viral-bacterial co-infection in adult hospitalized patients.EClinicalMedicine. 2021; 37: 100955
- Hong Kong: Age distribution from 2011 to 2021.(Available at:) (Accessed on September 13, 2022)
- The role of co-infections and secondary infections in patients with COVID-19.Pneumonia (Nathan). 2021; 13: 5
- Aerosol emission of adolescents voices during speaking, singing and shouting.PLoS One. 2021; 16: e0246819
- Aerosol emission and superemission during human speech increase with voice loudness.Sci Rep. 2019; 9: 2348
- The impact of vocalization loudness on COVID-19 transmission in indoor spaces.arXiv. 2009; 04060 (preprint arXiv): 2020
- SARS-CoV-2: eye protection might be the missing key.Lancet Microbe. 2021; 2: e173-e174
- Age-related vision changes: a primary care guide.Geriatrics. 1994; 49 (45; quiz 46-7): 37-42
- Association of Daily Wear of Eyeglasses With Susceptibility to Coronavirus Disease 2019 Infection.JAMA Ophthalmol. 2020; 138: 1196-1199
- Eyeglasses Reduce Risk of COVID-19 Infection.Vivo. 2021; 35: 1581-1582
- Underlying medical conditions associated with high risk for severe COVID-19: Information for healthcare providers.(Available at:) (Accessed on August 3, 2022)
- Science brief: Evidence used to update the list of underlying medical conditions that increase a person's risk of severe illness from COVID-19.(Available at:) (Accessed on August 3, 2022)
- Risk for COVID-19 infection, hospitalization, and death by age group.(Available at:) (Accessed on August 3, 2022)
- Race, Ethnicity, and Age Trends in Persons Who Died from COVID-19 - United States, May-August 2020.MMWR Morb Mortal Wkly Rep. 2020; 69: 1517-1521
Kenneth M, H.K. COVID-19: Clinical features. In: UpToDate, Hirsch M (Ed), UpToDate, Waltham, MA, Accessed on July 28, 2022. Published by UpToDate in Waltham, MA.
- Epidemiology of Covid-19 in a long-term care facility in king county, washington.N Engl J Med. 2020; 382: 2005-2011
- Risk factors for severe COVID-19 outcomes among persons aged ≥18 years who completed a primary COVID-19 vaccination series - 465 health care facilities, United States, december 2020-October 2021.MMWR Morb Mortal Wkly Rep. 2022; 71: 19-25
- Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa.Clin Infect Dis. 2019; 68: 895-902
- Influenza in long-term care facilities.Influenza Other Respir Viruses. 2017; 11: 356-366
- Severe Respiratory Illness Outbreak Associated with Human Coronavirus NL63 in a Long-Term Care Facility.Emerg Infect Dis. 2018; 24: 1964-1966
- How COVID-19 Spreads.(Available at:) (Accessed on July 28, 2022)
- Long-term care facilities and the coronavirus epidemic: practical guidelines for a population at highest risk.J Am Med Dir Assoc. 2020; 21: 569-571
- CDC guidance for living in close quarters.(Available at:) (Accessed on July 29, 2022)
- Dementia prevalence, a contextual factor associated with SARS-CoV-2 in veterans affairs community living centers.J Am Geriatr Soc. 2022; 70: 2973-2979
- Delirium in older people with COVID-19: clinical scenario and literature review.SN Compr Clin Med. 2020; 2: 1790-1797
- Risk Factors Associated With Mortality Among Residents With Coronavirus Disease 2019 (COVID-19) in Long-term Care Facilities in Ontario, Canada.JAMA Netw Open. 2020; 3: e2015957
- Policy Brief: COVID-19 and Assisted Living Facilities.J Am Geriatr Soc. 2020; 68: 1131-1135
- Clinical characteristics of COVID-19 in older adults. A retrospective study in long-term nursing homes in Catalonia.PLoS One. 2021; 16: e0255141
- Impact of COVID-19 on older adults and role of long-term care facilities during early stages of epidemic in Italy.Sci Rep. 2021; 11: 12530
- Severe Staffing And Personal Protective Equipment Shortages Faced By Nursing Homes During The COVID-19 Pandemic.Health Aff (Millwood). 2020; 39: 1812-1821
- Adjuvanted Influenza Vaccine and Influenza Outbreaks in US Nursing Homes: Results From a Pragmatic Cluster-Randomized Clinical Trial.Clin Infect Dis. 2021; 73: e4229-e4236
- Factors associated with SARS-CoV-2 infection and outbreaks in long-term care facilities in England: a national cross-sectional survey.Lancet Healthy Longev. 2021; 2: e129-e142
- COVID-19 in older adults.Aging Clin Exp Res. 2020; 32: 1199-1202
- Characteristics of and Important Lessons From the Coronavirus Disease 2019 (COVID-19) Outbreak in China: Summary of a Report of 72 314 cases from the chinese center for disease control and prevention.JAMA. 2020; 323: 1239-1242
- COVID-19 transmission risk factors.Pathog Glob Health. 2022; 116: 146-177
- Inoculum at the time of SARS-CoV-2 exposure and risk of disease severity.Int J Infect Dis. 2020; 97: 290-292
- Reinfections and COVID-19.(Available at:) (Accessed on Aug 02, 2022)
- COVID-19 after Vaccination: Possible Breakthrough Infection.(Available at:) (Accessed Aug 02, 2022)
- Risk for reinfection after SARS-CoV-2: a living, rapid review for american college of physicians practice points on the role of the antibody response in conferring immunity following sars-CoV-2 infection.Ann Intern Med. 2022; 175: 547-555
- Reinfection Rates Among Patients Who Previously Tested Positive for Coronavirus Disease 2019: A Retrospective Cohort Study.Clin Infect Dis. 2021; 73: 1882-1886
- Age-related differences in symptoms in older emergency department patients with COVID-19: Prevalence and outcomes in a multicenter cohort.J Am Geriatr Soc. 2022; 70: 1918-1930
- The immunology of asymptomatic SARS-CoV-2 infection: what are the key questions?.Nat Rev Immunol. 2021; 21: 762-768
- The durability of immunity against reinfection by SARS-CoV-2: a comparative evolutionary study.Lancet Microbe. 2021; 2: e666-e675
- Determining the Incidence of Asymptomatic SARS-CoV-2 Among Early Recipients of COVID-19 Vaccines (DISCOVER-COVID-19): a prospective cohort study of healthcare workers before, during and after vaccination.Clin Infect Dis. 2022; 74: 1275-1278
- Asymptomatic and Symptomatic SARS-CoV-2 Infections After BNT162b2 Vaccination in a Routinely Screened Workforce.JAMA. 2021; 325: 2500-2502
- Symptoms of COVID-19.(Available at:) (Accessed on July 27, 2022)
- Analysis of epidemiological and clinical features in older patients with coronavirus disease 2019 (COVID-19) outside Wuhan.Clin Infect Dis. 2020; 71: 740-747
- SARS-CoV-2 and COVID-19 in older adults: what we may expect regarding pathogenesis, immune responses, and outcomes.Geroscience. 2020; 42: 505-514
- Temperature in nursing home residents systematically tested for SARS-CoV-2.J Am Med Dir Assoc. 2020; 21: 895-899.e1
- Can we use temperature measurements to identify pre-symptomatic SARS-CoV-2 infection in nursing home residents?.J Am Geriatr Soc. 2022;
- Interim Infection Prevention and Control Recommendations to Prevent SARS-CoV-2 Spread in Nursing Homes.(Available at:) (Accessed August 04, 2022)
- Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility - King County, Washington, March 2020.MMWR Morb Mortal Wkly Rep. 2020; 69: 377-381
- Risk of persistent and new clinical sequelae among adults aged 65 years and older during the post-acute phase of SARS-CoV-2 infection: retrospective cohort study.Bmj. 2022; 376: e068414
- Risks of deep vein thrombosis, pulmonary embolism, and bleeding after covid-19: nationwide self-controlled cases series and matched cohort study.Bmj. 2022; 377: e069590
- Waning Immune Humoral Response to BNT162b2 Covid-19 Vaccine over 6 Months.N Engl J Med. 2021; 385: e84
- Factors associated with COVID-19-related death using OpenSAFELY.Nature. 2020; 584: 430-436
- Coronavirus Disease 2019 Case Surveillance - United States, January 22-May 30, 2020.MMWR Morb Mortal Wkly Rep. 2020; 69: 759-765
- Presymptomatic SARS-CoV-2 Infections and Transmission in a Skilled Nursing Facility.N Engl J Med. 2020; 382: 2081-2090
- Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis.Lancet. 2020; 395: 1973-1987
- Factors Affecting SARS-CoV-2 test discordance in skilled nursing facilities.J Am Med Dir Assoc. 2022; 23: 1279-1282
- Atypical presentations among older adults with COVID-19 disease: a need for broadening the differential diagnosis.Gerontol Geriatr Med. 2021; 7 (2333721421999313)
- A Comparative Study of Chest Computed Tomography Features in Young and Older Adults With Corona Virus Disease (COVID-19).J Thorac Imaging. 2020; 35: W97-W101
- Computed tomography findings and prognosis in older COVID-19 patients.BMC Geriatr. 2022; 22: 166
- Post–COVID Conditions Among Adult COVID-19 Survivors Aged 18–64 and ≥65 Years — United States, March 2020–November 2021.Morbidity Mortality Weekly Rep (Mmwr). 2022; 71: 713-717
- Nearly One in Five American Adults Who Have Had COVID-19 Still Have “Long COVID”.(Available at:) (Accessed on August 02, 2022)
- Long-COVID symptoms among veterans.J Am Geriatr Soc April. 2022; 70: S195
- Health outcomes in people 2 years after surviving hospitalisation with COVID-19: a longitudinal cohort study.Lancet Respir Med. 2022; 10: 863-876
- Short-term and Long-term Rates of Postacute Sequelae of SARS-CoV-2 Infection: A Systematic Review.JAMA Netw Open. 2021; 4: e2128568
- Sixty-Day Outcomes Among Patients Hospitalized With COVID-19.Ann Intern Med. 2021; 174: 576-578
- Trajectory of long covid symptoms after covid-19 vaccination: community based cohort study.BMJ. 2022; 377: e069676
- Challenges in defining long COVID: striking differences across literature, electronic health records, and patient-reported information.medRxiv. 2021;
- 6-month consequences of COVID-19 in patients discharged from hospital: a cohort study.Lancet. 2021; 397: 220-232
- More than 50 long-term effects of COVID-19: a systematic review and meta-analysis.Sci Rep. 2021; 11: 16144
- Long-COVID: An evolving problem with an extensive impact.S Afr Med J. 2020; 111: 10-12
- A longitudinal study of COVID-19 sequelae and immunity: baseline findings.Ann Intern Med. 2022; 175: 969-979
- Why does COVID-19 disproportionately affect older people?.Aging (Albany NY). 2020; 12: 9959-9981
- Comparative analysis of the risks of hospitalisation and death associated with SARS-CoV-2 omicron (B.1.1.529) and delta (B.1.617.2) variants in England: a cohort study.Lancet. 2022; 399: 1303-1312
- The proportion of SARS-CoV-2 infections that are asymptomatic : a systematic review.Ann Intern Med. 2021; 174: 655-662
- Estimated number of COVID-19 infections, hospitalizations, and deaths prevented among vaccinated persons in the US, december 2020 to september 2021.JAMA Netw Open. 2022; 5: e2220385
- Incident SARS-CoV-2 Infection among mRNA-vaccinated and unvaccinated nursing home residents.N Engl J Med. 2021; 385: 474-476
- Post-acute COVID-19 syndrome.Nat Med. 2021; 27: 601-615
- Persistent Symptoms in Patients After Acute COVID-19.JAMA. 2020; 324: 603-605
- Follow-up of adults with noncritical COVID-19 two months after symptom onset.Clin Microbiol Infect. 2021; 27: 258-263
- Patient outcomes after hospitalisation with COVID-19 and implications for follow-up: results from a prospective UK cohort.Thorax. 2021; 76: 399-401
- Post-acute COVID-19 syndrome. Incidence and risk factors: A Mediterranean cohort study.J Infect. 2021; 82: 378-383
- Postdischarge symptoms and rehabilitation needs in survivors of COVID-19 infection: A cross-sectional evaluation.J Med Virol. 2021; 93: 1013-1022
- Post-discharge persistent symptoms and health-related quality of life after hospitalization for COVID-19.J Infect. 2020; 81: e4-e6
- Burdens of post-acute sequelae of COVID-19 by severity of acute infection, demographics and health status.Nat Commun. 2021; 12: 6571
- Presymptomatic, asymptomatic and post-symptomatic transmission of SARS-CoV-2: joint British Infection Association (BIA), Healthcare Infection Society (HIS), Infection Prevention Society (IPS) and Royal College of Pathologists (RCPath) guidance.BMC Infect Dis. 2022; 22: 453
- WHO Covid-19 Case Definition.(Available at:) (Accessed on July 27, 2022)
- Coronavirus Disease 2019 (COVID-19) 2021 Case Definition.(Available at:) (Accessed on July 28, 2022)
- FDA Emergency Use Authorizations.(Available at:) (Accessed on July 28, 2022)
- The Laboratory Diagnosis of Coronavirus Disease 2019- Frequently Asked Questions.Clin Infect Dis. 2020; 71: 2996-3001
Caliendo AM, Hanson KE. COVID-19: Diagnosis. In: UpToDate, Hirsch M (Ed), UpToDate, Waltham, MA, Accessed on July 28, 2022.
- Coronavirus (COVID-19) Update: FDA Authorizes First COVID-19 Diagnostic Test Using Breath Samples.(Available at:) (Accessed on July 27, 2022)
- Interferon-γ release assay for accurate detection of severe acute respiratory syndrome coronavirus 2 t-cell response.Clin Infect Dis. 2021; 73: e3130-e3132