Postvaccination SARS-CoV-2 infections among skilled nursing facility residents and staff members — Chicago, Illinois, December 2020–March 2021

Abstract

This article describes 22 cases of breakthrough SARS-CoV-2 infection among over 14,000 fully vaccinated skilled nursing facility residents and staff. The majority of such infections were asymptomatic or were associated with mild symptoms, and there was no intra- facility spread related to these cases. This report suggests that postvaccination breakthrough infections are rare, but also confirms that vaccines do not offer 100% protection even in nonimmunosuppressed hosts, thus underscoring the need for studies of vaccine efficacy in immunosuppressed transplant recipients. This article describes 22 cases of breakthrough SARS-CoV-2 infection among over 14,000 fully vaccinated skilled nursing facility residents and staff. The majority of such infections were asymptomatic or were associated with mild symptoms, and there was no intra- facility spread related to these cases. This report suggests that postvaccination breakthrough infections are rare, but also confirms that vaccines do not offer 100% protection even in nonimmunosuppressed hosts, thus underscoring the need for studies of vaccine efficacy in immunosuppressed transplant recipients. Early studies suggest that COVID-19 vaccines protect against severe illness;1Thompson MG Burgess JL Naleway AL et al.Interim estimates of vaccine effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines in preventing SARS-CoV-2 infection among health care personnel, first responders, and other essential and frontline workers—eight U.S. locations, December 2020–March 2021.MMWR Morb Mortal Wkly Rep. 2021; 70: 495-500Crossref PubMed Scopus (398) Google Scholar however, postvaccination SARS-CoV-2 infections (i.e., breakthrough infections) can occur because COVID-19 vaccines do not offer 100% protection.2Baden LR El Sahly HM Essink B et al.COVE Study GroupEfficacy and safety of the mRNA-123 SARS-CoV-2 vaccine.N Engl J Med. 2021; 384: 403-416Crossref PubMed Scopus (4890) Google Scholar,3Polack FP Thomas SJ Kitchin N et al.C4591001 Clinical Trial GroupSafety and efficacy of the BNT162b2 mRNA Covid-19 vaccine.N Engl J Med. 2020; 383: 2603-2615Crossref PubMed Scopus (7305) Google Scholar Data evaluating the occurrence of breakthrough infections and impact of vaccination in decreasing transmission in congregate settings are limited. Skilled nursing facility (SNF) residents and staff members have been disproportionately affected by SARS-CoV-2, the virus that causes COVID-19,4Bagchi S Mak J Li Q et al.Rates of COVID-19 among residents and staff members in nursing homes—United States, May 25–November 22, 2020.MMWR Morb Mortal Wkly Rep. 2021; 70: 52-55Crossref PubMed Google Scholar,5Centers for Medicare & Medicaid ServicesCOVID-19 nursing home data. US Department of Health and Human Services, Centers for Medicare & Medicaid Services, Baltimore, MD2020Google Scholar and were prioritized for COVID-19 vaccination.6Dooling K McClung N Chamberland M et al.The Advisory Committee on Immunization Practices’ interim recommendation for allocating initial supplies of COVID-19 vaccine—United States, 2020.MMWR Morb Mortal Wkly Rep. 2020; 69: 1857-1859Crossref PubMed Google Scholar,7Gharpure R Guo A Bishnoi CK et al.Early COVID-19 first-dose vaccination coverage among residents and staff members of skilled nursing facilities participating in the Pharmacy Partnership for Long-Term Care Program—United States, December 2020–January 2021.MMWR Morb Mortal Wkly Rep. 2021; 70: 178-182Crossref PubMed Google Scholar Starting December 28, 2020, all 78 Chicago-based SNFs began COVID-19 vaccination clinics over several weeks through the federal Pharmacy Partnership for Long-Term Care Program (PPP).1 In February 2021, through routine screening, the Chicago Department of Public Health (CDPH) identified a SARS-CoV-2 infection in a SNF resident >14 days after receipt of the second dose of a two-dose COVID-19 vaccination series. SARS-CoV-2 cases, vaccination status, and possible vaccine breakthrough infections were identified by matching facility reports with state case and vaccination registries. Among 627 persons with SARS-CoV-2 infection across 75 SNFs since vaccination clinics began, 22 SARS-CoV-2 infections were identified among 12 residents and 10 staff members across 15 facilities ≥14 days after receiving their second vaccine dose (i.e., breakthrough infections in fully vaccinated persons). Nearly two-thirds (14 of 22; 64%) of persons with breakthrough infections were asymptomatic; two residents were hospitalized because of COVID-19, and one died. No facility-associated secondary transmission occurred. Although few SARS-CoV-2 infections in fully vaccinated persons were observed, these cases demonstrate the need for SNFs to follow recommended routine infection prevention and control practices and promote high vaccination coverage among SNF residents and staff members. CDPH monitors SNF SARS-CoV-2 infections using a data triangulation method that matches the SARS-CoV-2 test results from nucleic acid amplification tests (NAATs, such as reverse transcription–polymerase chain reaction [RT-PCR]) and antigen tests reported to the Illinois’ National Electronic Disease Surveillance System with facility-reported line lists of SARS-CoV-2 test results from routine screening testing.2 In February 2021, CDPH began matching records to Illinois’ Comprehensive Automated Immunization Registry Exchange to identify breakthrough infections. After identifying SARS-CoV-2 infection in a SNF resident 16 days after receipt of a second vaccine dose, CDPH initiated an investigation to quantify breakthrough infections across all facilities, evaluate symptoms and clinical outcomes, and assess potential secondary transmission. Vaccine effectiveness was not evaluated. A facility’s investigation period started on its first vaccination clinic date and ended March 31, 2021.3 A confirmed case of SARS-CoV-2 infection was defined as a positive SARS-CoV-2 NAAT or antigen test result from a respiratory specimen collected from a resident or staff member during the investigation period. Consistent with CDC guidance, a vaccine breakthrough infection in a resident or staff member was defined as a receipt of a positive SARS-CoV-2 NAAT or antigen test result from a respiratory specimen collected ≥14 days after completing the two-dose COVID-19 vaccination series.4 Infection prevention specialists conducted case investigations to assess symptoms, clinical outcomes, and close contact information. SARS-CoV-2 incidence during the investigation period was assessed across four groups based on vaccination status at the time a positive respiratory specimen was collected: (1) unvaccinated (never received a COVID-19 vaccine dose); (2) partially vaccinated (received one dose of a two-dose series); (3) vaccinated but not immune (received two doses of a two-dose series but <14 days had elapsed since the second dose); and (4) fully vaccinated (received two doses of a two-dose series and ≥14 days had elapsed since the second dose). In addition to routine facility follow-up, CDPH actively monitored facilities with breakthrough infections for 28 days to identify whether any new cases occurred in close contacts of the person with breakthrough infection.5 Analyses were completed using SAS (version 9.4; SAS Institute). This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.6 During the investigation period, an estimated 7931 SNF residents and 6834 staff members received two doses of COVID-19 vaccine. A total of 627 confirmed SARS-CoV-2 infections were identified across 75 of the 78 Chicago-based SNFs, including 353 (56%) among residents and 274 (44%) among staff members during the investigation period (Table 1). Three facilities had no confirmed SARS-CoV-2 infections after their first vaccination clinic. Approximately one half (47%) of resident cases occurred in men, 42% were in non-Hispanic Black persons, and the median age was 71 years. More than two-thirds (72%) of staff member cases were in women, 38% were in non-Hispanic Black persons, and the median age was 42 years. Among the 627 cases, 447 (71%) occurred in unvaccinated persons, 145 (23%) in partially vaccinated persons, 13 (2%) in vaccinated but not immune persons, and 22 (4%) in fully vaccinated persons (Figure 1). These breakthrough infections occurred in 12 residents and 10 staff members and accounted for 16% (22 of 136) of SNF-associated cases occurring across all facilities ≥14 days after the second vaccination clinic at the respective facilities. No demographic or clinical differences were observed by vaccination status.TABLE 1Number and percentage of skilled nursing facility residents and staff members with a positive confirmed SARS-CoV-2 test result, by demographic and clinical characteristics and vaccination status — Chicago, Illinois, December 2020–March 2021CharacteristicVaccination status of residents and staff members with SARS-CoV-2 infections, no. (column %)Total (n = 627)UnvaccinatedaUnvaccinated: received no COVID-19 vaccine doses; partially vaccinated: received one dose; vaccinated but not immune: received two doses but <14 days had elapsed since receipt of second dose; and fully vaccinated with breakthrough infection: received two doses and then received a positive SARS-CoV-2 test result ≥14 days after receipt of the second dose. (n = 447)Partially vaccinatedaUnvaccinated: received no COVID-19 vaccine doses; partially vaccinated: received one dose; vaccinated but not immune: received two doses but <14 days had elapsed since receipt of second dose; and fully vaccinated with breakthrough infection: received two doses and then received a positive SARS-CoV-2 test result ≥14 days after receipt of the second dose. (n = 145)Vaccinated but not immuneaUnvaccinated: received no COVID-19 vaccine doses; partially vaccinated: received one dose; vaccinated but not immune: received two doses but <14 days had elapsed since receipt of second dose; and fully vaccinated with breakthrough infection: received two doses and then received a positive SARS-CoV-2 test result ≥14 days after receipt of the second dose. (n = 13)Fully vaccinated with breakthrough infectionaUnvaccinated: received no COVID-19 vaccine doses; partially vaccinated: received one dose; vaccinated but not immune: received two doses but <14 days had elapsed since receipt of second dose; and fully vaccinated with breakthrough infection: received two doses and then received a positive SARS-CoV-2 test result ≥14 days after receipt of the second dose. (n = 22)Median age (IQR)60.0 (43.0–73.0)57.0 (39.0–71.0)65.0 (50.0–79.0)66.0 (58.0–79.0)61.5 (41.0–73.0)SexFemale376 (60.0)265 (59.3)89 (61.4)7 (53.9)15 (68.2)Male237 (37.8)168 (37.6)56 (38.6)6 (46.2)7 (31.8)Unknown14 (2.2)14 (3.1)0 (–)0 (–)0 (–)Race/ethnicityHispanic/Latino58 (9.3)37 (8.3)16 (11.0)1 (7.7)4 (18.2)Asian, non-Hispanic24 (3.8)11 (2.5)9 (6.2)1 (7.7)3 (13.6)Black, non-Hispanic252 (40.2)193 (43.2)44 (30.3)7 (53.9)8 (36.4)White, non-Hispanic144 (23.0)79 (17.7)55 (37.9)3 (23.1)7 (31.8)Other,bPersons with the following races listed in I-NEDSS as American Indian or Alaska Native, Native Hawaiian or other Pacific Islander, other, or multiracial were categorized as non-Hispanic other. non-Hispanic16 (2.6)12 (2.7)4 (2.8)0 (–)0 (–)Unknown133 (21.2)115 (25.7)17 (11.7)1 (7.7)0 (–)RoleResident353 (56.3)235 (52.6)97 (66.9)9 (69.2)12 (54.6)Staff member274 (43.7)212 (47.4)48 (33.1)4 (30.8)10 (45.5)SymptomscData on symptoms were extracted from I-NEDSS for unvaccinated, partially vaccinated, and vaccinated but not immune persons. Most COVID-19 case reports are entered into I-NEDSS through electronic laboratory reporting and provide minimal information (e.g., name, date of birth, and laboratory test and results) needed to meet reporting requirements. Data on symptoms in persons with breakthrough infections were supplemented with details from case investigations, which were not completed for nonbreakthrough cases. Symptom status for many persons with nonbreakthrough infection cases is unknown.Yes92 (14.7)62 (13.9)21 (14.5)1 (7.7)8 (36.4)No34 (5.4)15 (3.4)5 (3.5)0 (–)14 (63.6)Unknown501 (79.9)370 (82.8)119 (82.1)12 (92.3)0 (–)HospitalizationsYes123 (19.6)90 (20.1)27 (18.6)2 (15.4)4 (18.2)dTwo residents were hospitalized for COVID-19–related reasons. Two additional residents were hospitalized for non-COVID-19–related reasons.No504 (80.4)357 (79.9)118 (81.4)11 (84.6)18 (81.8)DeathsYes21 (3.4)14 (3.1)6 (4.1)0 (–)1 (4.6)No606 (96.7)433 (96.9)139 (95.9)13 (100.0)21 (95.5)Previous positive SARS-CoV-2 resultYes41 (6.5)22 (4.9)9 (6.2)4 (30.8)6 (27.3)No586 (93.5)425 (95.1)136 (93.8)9 (69.2)16 (72.7)Abbreviations: Illinois’ National Electronic Disease Surveillance received no COVID-19 vaccine doses; partially vaccinated: received one dose; vaccinated but not immune: received two doses but <14 days had elapsed since receipt of second dose; and fully vaccinated with breakthrough infection: received two doses and then received a positive SARS-CoV-2 test result ≥14 days after receipt of the second with the following races listed in I-NEDSS as American Indian or Alaska Native, Native Hawaiian or other Pacific Islander, other, or multiracial were categorized as non-Hispanic Data on symptoms were extracted from I-NEDSS for unvaccinated, partially vaccinated, and vaccinated but not immune persons. Most COVID-19 case reports are entered into I-NEDSS through electronic laboratory reporting and provide minimal information (e.g., name, date of birth, and laboratory test and results) needed to meet reporting requirements. Data on symptoms in persons with breakthrough infections were supplemented with details from case investigations, which were not completed for nonbreakthrough cases. Symptom status for many persons with nonbreakthrough infection cases is Two residents were hospitalized for COVID-19–related reasons. Two additional residents were hospitalized for non-COVID-19–related reasons. in a new Illinois’ National Electronic Disease Surveillance Among the 22 breakthrough infections, were in persons received as of routine screening, and four occurred in residents received a or Among the breakthrough infections identified during routine screening, were 10 residents were receiving from the staff members at all facilities were receiving at The median from second dose to of a positive SARS-CoV-2 specimen was days The median positive NAAT result and test result was days vaccination coverage among residents and staff members at facilities with breakthrough infections from to and to Among the 15 facilities with breakthrough cases, for unvaccinated and vaccinated residents were of and of Among staff for unvaccinated and vaccinated persons were of and of facilities reported a total of confirmed cases 28 days after initial breakthrough infection at a facility (Table No facility-associated secondary transmission was to have occurred because the new cases that occurred after the initial breakthrough infection were not close contacts of the persons with breakthrough is and staff members of skilled nursing facilities are recommended to COVID-19 vaccine as a is by possible breakthrough SARS-CoV-2 infections occurred among fully vaccinated persons ≥14 days after their second dose of COVID-19 vaccine. of persons were A of persons with breakthrough infection two COVID-19–related and one occurred. No facility-associated secondary transmission was are the for health vaccination and follow recommended COVID-19 infection prevention and control including following of residents and staff and of nursing facility residents and staff members with SARS-CoV-2 breakthrough of a positive SARS-CoV-2 NAAT (e.g., reverse transcription–polymerase chain or antigen test result from a respiratory specimen collected ≥14 days after completing the two-dose COVID-19 vaccination series. by facility and clinical characteristics — Chicago, Illinois, December 2020–March and staff members with breakthrough age of days second vaccine dose and positive specimen are for that were by the laboratory and for positive SARS-CoV-2 test of days initial and positive test of days SARS-CoV-2 test result and postvaccination positive of facility cases occurring after breakthrough identified a from the date of specimen for the breakthrough facilities with breakthrough infections, and new facility cases listed of cases close a new case in a facility was infection prevention specialists whether the person with the case to a close contact of the person with the breakthrough Data in the of cases in persons that the of a close contact and occurred after of the breakthrough infection as of not COVID-19 had a positive SARS-CoV-2 test result 16 days after receiving the second dose of COVID-19 which was an to the for new of The positive result have been related to an of days after the second dose. COVID-19 was not associated with symptoms, and resident was because the case the breakthrough infection This resident not a breakthrough infection because is of SARS-CoV-2 infection not COVID-19 had a positive SARS-CoV-2 test result and was hospitalized for non-COVID-19–related including and a infection related to a COVID-19 was hospitalized for COVID-19–related because of and of in with at on the case by the of and had COVID-19 was using the Illinois’ National Electronic Disease Surveillance No positive SARS-CoV-2 were identified for of or COVID-19 was hospitalized for COVID-19–related because of and SARS-CoV-2 test result was and resident received a of and in the care for respiratory infections including B and infection were also The resident days after was hospitalized for COVID-19–related because of and SARS-CoV-2 test result was and resident received a of and in the care for respiratory infections including B and infection were also The resident days after not nucleic acid amplification = of of a positive SARS-CoV-2 NAAT (e.g., reverse transcription–polymerase chain or antigen test result from a respiratory specimen collected ≥14 days after completing the two-dose COVID-19 vaccination are for that were by the laboratory and for identified a from the date of specimen for the breakthrough facilities with breakthrough infections, and new facility cases listed a new case in a facility was infection prevention specialists whether the person with the case to a close contact of the person with the breakthrough Data in the of cases in persons that the of a close contact and occurred after of the breakthrough infection as of had a positive SARS-CoV-2 test result 16 days after receiving the second dose of COVID-19 which was an to the for new of The positive result have been related to an of days after the second dose. COVID-19 was not associated with symptoms, and resident was because the case the breakthrough infection This resident not a breakthrough infection because is of SARS-CoV-2 infection had a positive SARS-CoV-2 test result and was hospitalized for non-COVID-19–related including and a infection related to a was hospitalized for COVID-19–related because of and of in with at on the case by the of and had COVID-19 was using the Illinois’ National Electronic Disease Surveillance No positive SARS-CoV-2 were identified for was hospitalized for COVID-19–related because of and SARS-CoV-2 test result was and resident received a of and in the care for respiratory infections including B and infection were also The resident days after in a new and staff members of skilled nursing facilities are recommended to COVID-19 vaccine as a possible breakthrough SARS-CoV-2 infections occurred among fully vaccinated persons ≥14 days after their second dose of COVID-19 vaccine. of persons were A of persons with breakthrough infection two COVID-19–related and one occurred. No facility-associated secondary transmission was SNFs vaccination and follow recommended COVID-19 infection prevention and control including following of residents and staff and of not nucleic acid amplification = of Among the 22 persons with breakthrough infections, residents and staff were asymptomatic (Table Three persons and had two and had and and had residents were two and for COVID-19–related and two and for to one resident died. received a of days after receiving the second COVID-19 vaccine dose and days receiving a positive SARS-CoV-2 test result (Table Although the of the positive SARS-CoV-2 test result the of a breakthrough the clinical that the infection occurred <14 days after the second dose. was hospitalized for and of in with and respiratory symptoms and received a of This had a positive SARS-CoV-2 test result on and had B and a infection and days after The listed of COVID-19 infection as of were and Among 12 from with breakthrough infections, were of persons with breakthrough infections had a positive SARS-CoV-2 test result days the including persons had test results the positive results and at one NAAT result <14 days the postvaccination positive test persons were asymptomatic during the second for were SNF residents and 10 staff members had positive SARS-CoV-2 test results ≥14 days after receiving a second COVID-19 vaccine dose were suggest and no facility-associated secondary transmission was Two residents with breakthrough infections one of because of infections. Although rare, postvaccination breakthrough infection can occur because COVID-19 vaccines do not offer 100% protection.2Baden LR El Sahly HM Essink B et al.COVE Study GroupEfficacy and safety of the mRNA-123 SARS-CoV-2 vaccine.N Engl J Med. 2021; 384: 403-416Crossref PubMed Scopus (4890) Google Scholar,3Polack FP Thomas SJ Kitchin N et al.C4591001 Clinical Trial GroupSafety and efficacy of the BNT162b2 mRNA Covid-19 vaccine.N Engl J Med. 2020; 383: 2603-2615Crossref PubMed Scopus (7305) Google Scholar Early studies suggest that COVID-19 vaccines protect against severe and at preventing MG Burgess JL Naleway AL et al.Interim estimates of vaccine effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines in preventing SARS-CoV-2 infection among health care personnel, first responders, and other essential and frontline workers—eight U.S. locations, December 2020–March 2021.MMWR Morb Mortal Wkly Rep. 2021; 70: 495-500Crossref PubMed Scopus (398) Google Scholar however, data on the impact of vaccination on transmission in congregate settings are limited. In persons infections the case of a breakthrough infection have had positive NAAT results after initial however, had confirmed interim test data are needed to breakthrough infections from of infections and to whether persons with breakthrough infections can The results in report the of COVID-19 vaccination in congregate settings such as fully vaccinated persons were not not have symptoms, and not have severe the of positive NAAT results during the investigation period, breakthrough infections not to secondary transmission at these facilities. of residents and staff members in these settings in to or investigations is also of vaccination status, because these persons have asymptomatic A that vaccination an estimated effectiveness of against SARS-CoV-2 infection among SNF residents >14 days after the first dose through days after the second A et of the COVID-19 vaccine among residents of two skilled nursing facilities COVID-19 December 2021.MMWR Morb Mortal Wkly Rep. 2021; 70: PubMed Scopus Google Scholar studies are needed to assess the impact of vaccination in SNFs and to vaccination in settings that persons, and persons with of SARS-CoV-2 infection with clinical efficacy data. vaccinated asymptomatic persons can SARS-CoV-2 is also facilities to residents to after close contact with an Vaccine effectiveness estimates for prevention of SARS-CoV-2 infection and COVID-19 were not because CDPH not have to SNF electronic the to data from facilities on all residents and staff members and to among vaccinated and unvaccinated persons were not not have the to provide line lists and vaccination information for residents and staff members. The in report are to at four whether with a breakthrough infection and a positive SARS-CoV-2 test result had a or persons with from infection was not SARS-CoV-2 is in respiratory of with with infection control 2021; PubMed Scopus Google Scholar In addition to two SARS-CoV-2 tests days respiratory are needed that their can Data such as to confirmed cases and clinical can provide for but do not identify vaccination data in report are to Chicago residents and persons vaccinated in data were for staff members were not Chicago residents and were vaccinated data or reporting to an of breakthrough infections. were for to evaluate possible results are and not SNFs to follow recommended infection prevention and control including of persons with confirmed cases, of residents have had close contact with persons with confirmed cases, routine and of residents and staff and of of vaccination high vaccination coverage among residents and staff members is also to for transmission facilities and among persons not have after residents and staff members of all Chicago-based skilled nursing facilities, including the and infection prevention staff at the facilities with breakthrough infections. have completed and the Committee of for of potential of No potential of were among Health Care and to provide COVID-19 vaccination of residents and staff members at care facilities, including facilities to test residents at members were also to with based on and other of members at all Chicago-based SNFs were at February then February then March through the of investigation In to a facility (i.e., a resident or staff member with a case the all staff members and residents received a positive SARS-CoV-2 test days are to at days no new cases occur for at the time a breakthrough infection was of resident at the 15 SNFs from to of staff member from to vaccination clinics occurred during December 28, 2020–January were in the infection occurred the first clinic date at their respective facility and March 31, COVID-19 vaccination was at Chicago-based SNFs through the federal residents and two staff members received COVID-19 vaccine through Chicago-based vaccine not participating in the federal or facilities the of breakthrough infection and staff members were from the investigation had received a positive SARS-CoV-2 test result from December 28 through the date of their facility’s first vaccination clinic or a initial positive SARS-CoV-2 test result days their SARS-CoV-2 test close contact was defined as of a person for over a period, of staff close contact was defined as of a person for over a period one or persons were 42 et residents and staff members had received COVID-19 vaccine (i.e., unvaccinated and had received one COVID-19 vaccine dose of a two-dose series (i.e., partially vaccinated were categorized as and staff members had received two COVID-19 vaccine doses of a two-dose series and <14 days or ≥14 days had elapsed (i.e., vaccinated but not immune and fully vaccinated persons, were categorized as vaccination data were for residents and staff members received two doses of COVID-19 vaccine and not have a SARS-CoV-2 In the persons received two doses <14 days or ≥14 days was not identified a from the date of specimen for the breakthrough facilities with breakthrough infections, and new facility cases listed of 2021, of the cases were breakthrough of which are listed and occurred during the investigation period. were categorized as or based on the National Surveillance System and of and of

Topics & Concepts