biostudies-literatureHall VMedical Research CouncilNational Institute for Health Research (NIHR)1207-1220https://www.ebi.ac.uk/biostudies/studies/S-EPMC8908850biostudies-literatureUnknown386(13)<h4>Background</h4>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.<h4>Methods</h4>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.<h4>Results</h4>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.<h4>Conclusions</h4>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. (Funded by the U.K. Health Security Agency and others; ISRCTN Registry number, ISRCTN11041050.).The New England journal of medicineProtection against SARS-CoV-2 after Covid-19 Vaccination and Previous Infection.PMC8908850NIHR300791MC_UU_00002/11Williams MMeda MCarr ECromey LYoung CWilliams KCowling PJames KCutler SHoad ISubbe CSaei AAuckland CKlenerman PPatel MLester YTodd Ade Lacy EHouston AHarwood JHall VTemple-Purcell RRussell JDonaghy TCastillo-Olivares JTimeyin JO'Connell AMFowles-Gutierrez NGillson NGibson AStrong-Sheldrake SMeisner SRoebuck AHatton JChitalia NPai SGibson HHacon COtter ADKyffin RWhite NHoward JLongfellow RTurner AFinlayson LHettiarachchi NJones CMouland JMalcolm MHoward MWong NPritchard Jones RGallagher EAldridge NEasom NBishop JHamer SPlant ALoughrey CThornton ADuncan CGould IBeekes MNeill CMaxwell VAdebiyi OHinch SShorten RParmar CMilward SGreen MGray KFothergill LSergenson NTonge SGeen JEdmunds TMirfenderesky MVilimiene NMcwilliam SHicks BKhanduri SThompson CBoss DTranquillini CTilley RFowler SDobbie LCourt KPepperell JKhawam JWatt ASevern AHilton DOtter ADe Lacy EAshby HTarr EEllis YAgwuh KChaudhuri RZambon MLazarus RDhasmana DHowell KGoodwin JWilkinson BLewis KDawson JDemocratis JBoyd GWiselka MRajgopal ABarnes TLewis TFaris BTurtle LBrand SO'Kelly AGormley STazzyman SDave AIslam JMercer PBarnes ESajedi NBhayani JBrowne DMonk EHayes AAeron-Thomas JMurphy MRidley PBrookes CPegg CRichter AButt GCreer SSIREN Study GroupMunro Kde Silva TCrooks NBurns PFraile EHolliday KBaillon SPottinger GChenoweth HStevens GBurns KPayne BTrinick TLarru BHarris EPagett KAshcroft JDunachie SIrvine VSubhroOsuji BAmbalkar SLeach MPiercy CBrown CSTelfer ASelassie AGame FSinclair JJory HRowe CPrince SBrake SHughes LBroadley AWellington ESinclair CMcAdam CMoran KSinclair AMoody AHanison EStewart BColeman TDelgado DMatthews RKerrison CPalmarini MBexley AReeks CBoard STaylor-Kerr AGiles JZheng QRichardson LAdeboyeku DNimako KWycherley DElumogo NCoke LGuha SJohnston FBagary MWeir JMatuluko ATyson LProtaschik YNorthfield JStafford CMilligan IHewson JCowley AWestwell FWilson-Davies EThomas CThomas ARokakis ADel Rosario ILee MO'Kane MSzewczyk MKirwan PDay JCorrigan DWhileman AShipman KCole MHopkins SPowell JAndrews NThomas RBooth MCross EPepper SPrince Plackal RLaugharne RHalkes MLedger JRodger AWadams BHorsley AHarbham PPrice LFroude SPothecary CReynolds TBlack KBoulos AMahabir NStewart SFrieslick JLinley ECochrane AHuang YCalbraith DNeave AColes HClarke APrice CCharlett AMackay SBrown ABaillie JKCarroll HSierra RElliott JHanna ESubudhi CAhmad SGabriel CYates JWarren SBarclay WJorgenson ABrown CWatson EBaxendale HSemper ABerry LAkhtar SSach LHolmes CChand MBooth LBBrooks TBaines DGoldberg DHeeney JAtti AHo ADiaz SThemistocleous YWinchester SCrosby-Nwaobi RMahungu TWootton DHarvey DDuff CWard EPenn RRamsay MConneely PNorman CQazzafi ZConneely JKalakonda NTempleton KTomlinson JDitchfield LInsalata FBurton BOmar ZEtell Kirby ESheridan EPlanche THarrison GRobinson LKunhunny SCampbell MChawla AD'Arcangelo SBakker PGrant APickard GJohnstone HChapman RShah AGraves JCameron EBrown KJoseph MBeale RColton JFavager CKemsley PFoulkes SAllsop LRowley SKhan SfalseProtection against SARS-CoV-2 after Covid-19 Vaccination and Previous Infection.<h4>Background</h4>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.<h4>Methods</h4>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.<h4>Results</h4>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.<h4>Conclusions</h4>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. (Funded by the U.K. Health Security Agency and others; ISRCTN Registry number, ISRCTN11041050.).2022-01-01T00:00:00Z2022 Mar2025-04-04T20:50:35.482Z2025-04-04T20:50:35.482ZS-EPMC89088503517205110.1056/NEJMoa2118691