TY - JOUR
T1 - Protection against SARS-CoV-2 after Covid-19 vaccination and previous infection
AU - SIREN Study Group
AU - Hall, Victoria
AU - Foulkes, Sarah
AU - Insalata, Ferdinando
AU - Kirwan, Peter
AU - Saei, Ayoub
AU - Atti, Ana
AU - Wellington, Edgar
AU - Khawam, Jameel
AU - Munro, Katie
AU - Cole, Michelle
AU - Tranquillini, Caio
AU - Taylor-Kerr, Andrew
AU - Hettiarachchi, Nipunadi
AU - Calbraith, Davina
AU - Sajedi, Noshin
AU - Milligan, Iain
AU - Themistocleous, Yrene
AU - Corrigan, Diane
AU - Cromey, Lisa
AU - Price, Lesley
AU - Stewart, Sally
AU - de Lacy, Elen
AU - Norman, Chris
AU - Linley, Ezra
AU - Otter, Ashley D
AU - Semper, Amanda
AU - Hewson, Jacqueline
AU - D'Arcangelo, Silvia
AU - Chand, Meera
AU - Brown, Colin S
AU - Brooks, Tim
AU - Islam, Jasmin
AU - Charlett, Andre
AU - Hopkins, Susan
AU - Dhasmana, Devesh J
N1 - Supported by the U.K. Health Security Agency, the U.K. Department of Health and Social Care (with contributions from the governments in Northern Ireland, Wales, and Scotland), the National Institute for Health Research, and grants from the Medical Research Council.
PY - 2022/3/31
Y1 - 2022/3/31
N2 - Background: The duration and effectiveness of immunity from infection with and vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are relevant to pandemic policy interventions, including the timing of vaccine boosters.Methods: We investigated the duration and effectiveness of immunity in a prospective cohort of asymptomatic health care workers in the United Kingdom who underwent routine polymerase-chain-reaction (PCR) testing. Vaccine effectiveness (≤10 months after the first dose of vaccine) and infection-acquired immunity were assessed by comparing the time to PCR-confirmed infection in vaccinated persons with that in unvaccinated persons, stratified according to previous infection status. We used a Cox regression model with adjustment for previous SARS-CoV-2 infection status, vaccine type and dosing interval, demographic characteristics, and workplace exposure to SARS-CoV-2.Results: Of 35,768 participants, 27% (9488) had a previous SARS-CoV-2 infection. Vaccine coverage was high: 95% of the participants had received two doses (78% had received BNT162b2 vaccine [Pfizer-BioNTech] with a long interval between doses, 9% BNT162b2 vaccine with a short interval between doses, and 8% ChAdOx1 nCoV-19 vaccine [AstraZeneca]). Between December 7, 2020, and September 21, 2021, a total of 2747 primary infections and 210 reinfections were observed. Among previously uninfected participants who received long-interval BNT162b2 vaccine, adjusted vaccine effectiveness decreased from 85% (95% confidence interval [CI], 72 to 92) 14 to 73 days after the second dose to 51% (95% CI, 22 to 69) at a median of 201 days (interquartile range, 197 to 205) after the second dose; this effectiveness did not differ significantly between the long-interval and short-interval BNT162b2 vaccine recipients. At 14 to 73 days after the second dose, adjusted vaccine effectiveness among ChAdOx1 nCoV-19 vaccine recipients was 58% (95% CI, 23 to 77) - considerably lower than that among BNT162b2 vaccine recipients. Infection-acquired immunity waned after 1 year in unvaccinated participants but remained consistently higher than 90% in those who were subsequently vaccinated, even in persons infected more than 18 months previously.Conclusions: Two doses of BNT162b2 vaccine were associated with high short-term protection against SARS-CoV-2 infection; this protection waned considerably after 6 months. Infection-acquired immunity boosted with vaccination remained high more than 1 year after infection.
AB - Background: The duration and effectiveness of immunity from infection with and vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are relevant to pandemic policy interventions, including the timing of vaccine boosters.Methods: We investigated the duration and effectiveness of immunity in a prospective cohort of asymptomatic health care workers in the United Kingdom who underwent routine polymerase-chain-reaction (PCR) testing. Vaccine effectiveness (≤10 months after the first dose of vaccine) and infection-acquired immunity were assessed by comparing the time to PCR-confirmed infection in vaccinated persons with that in unvaccinated persons, stratified according to previous infection status. We used a Cox regression model with adjustment for previous SARS-CoV-2 infection status, vaccine type and dosing interval, demographic characteristics, and workplace exposure to SARS-CoV-2.Results: Of 35,768 participants, 27% (9488) had a previous SARS-CoV-2 infection. Vaccine coverage was high: 95% of the participants had received two doses (78% had received BNT162b2 vaccine [Pfizer-BioNTech] with a long interval between doses, 9% BNT162b2 vaccine with a short interval between doses, and 8% ChAdOx1 nCoV-19 vaccine [AstraZeneca]). Between December 7, 2020, and September 21, 2021, a total of 2747 primary infections and 210 reinfections were observed. Among previously uninfected participants who received long-interval BNT162b2 vaccine, adjusted vaccine effectiveness decreased from 85% (95% confidence interval [CI], 72 to 92) 14 to 73 days after the second dose to 51% (95% CI, 22 to 69) at a median of 201 days (interquartile range, 197 to 205) after the second dose; this effectiveness did not differ significantly between the long-interval and short-interval BNT162b2 vaccine recipients. At 14 to 73 days after the second dose, adjusted vaccine effectiveness among ChAdOx1 nCoV-19 vaccine recipients was 58% (95% CI, 23 to 77) - considerably lower than that among BNT162b2 vaccine recipients. Infection-acquired immunity waned after 1 year in unvaccinated participants but remained consistently higher than 90% in those who were subsequently vaccinated, even in persons infected more than 18 months previously.Conclusions: Two doses of BNT162b2 vaccine were associated with high short-term protection against SARS-CoV-2 infection; this protection waned considerably after 6 months. Infection-acquired immunity boosted with vaccination remained high more than 1 year after infection.
KW - Adaptive immunity/immunology
KW - Asymptomatic diseases
KW - BNT162 vaccine/therapeutic use
KW - COVID-19/diagnosis
KW - COVID-19 nucleic acid testing
KW - COVID-19 vaccines/immunology
KW - ChAdOx1 nCoV-19/therapeutic use
KW - Health personnel
KW - Humans
KW - Prospective studies
KW - SARS-CoV-2
KW - United Kingdom
KW - Vaccination/methods
KW - Vaccine efficacy
U2 - 10.1056/NEJMoa2118691
DO - 10.1056/NEJMoa2118691
M3 - Article
C2 - 35172051
SN - 0028-4793
VL - 386
SP - 1207
EP - 1220
JO - New England Journal of Medicine
JF - New England Journal of Medicine
IS - 13
ER -