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1.
Emerg Infect Dis ; 29(1)2022 Dec 01.
Article in English | MEDLINE | ID: covidwho-2230070

ABSTRACT

Since June 2020, the SARS-CoV-2 Immunity and Reinfection Evaluation (SIREN) study has conducted routine PCR testing in UK healthcare workers and sequenced PCR-positive samples. SIREN detected increases in infections and reinfections during Omicron subvariant waves contemporaneous with national surveillance. SIREN's sentinel surveillance methods can be used for variant surveillance.

2.
J Infect ; 85(5): 545-556, 2022 11.
Article in English | MEDLINE | ID: covidwho-2007862

ABSTRACT

OBJECTIVES: To investigate serological differences between SARS-CoV-2 reinfection cases and contemporary controls, to identify antibody correlates of protection against reinfection. METHODS: We performed a case-control study, comparing reinfection cases with singly infected individuals pre-vaccination, matched by gender, age, region and timing of first infection. Serum samples were tested for anti-SARS-CoV-2 spike (anti-S), anti-SARS-CoV-2 nucleocapsid (anti-N), live virus microneutralisation (LV-N) and pseudovirus microneutralisation (PV-N). Results were analysed using fixed effect linear regression and fitted into conditional logistic regression models. RESULTS: We identified 23 cases and 92 controls. First infections occurred before November 2020; reinfections occurred before February 2021, pre-vaccination. Anti-S levels, LV-N and PV-N titres were significantly lower among cases; no difference was found for anti-N levels. Increasing anti-S levels were associated with reduced risk of reinfection (OR 0·63, CI 0·47-0·85), but no association for anti-N levels (OR 0·88, CI 0·73-1·05). Titres >40 were correlated with protection against reinfection for LV-N Wuhan (OR 0·02, CI 0·001-0·31) and LV-N Alpha (OR 0·07, CI 0·009-0·62). For PV-N, titres >100 were associated with protection against Wuhan (OR 0·14, CI 0·03-0·64) and Alpha (0·06, CI 0·008-0·40). CONCLUSIONS: Before vaccination, protection against SARS-CoV-2 reinfection was directly correlated with anti-S levels, PV-N and LV-N titres, but not with anti-N levels. Detectable LV-N titres were sufficient for protection, whilst PV-N titres >100 were required for a protective effect. TRIAL REGISTRATION NUMBER: ISRCTN11041050.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Viral , COVID-19/prevention & control , Case-Control Studies , Humans , Reinfection/prevention & control , Vaccination
3.
BMJ Open ; 12(6): e054336, 2022 06 28.
Article in English | MEDLINE | ID: covidwho-1909750

ABSTRACT

INTRODUCTION: Understanding the effectiveness and durability of protection against SARS-CoV-2 infection conferred by previous infection and COVID-19 is essential to inform ongoing management of the pandemic. This study aims to determine whether prior SARS-CoV-2 infection or COVID-19 vaccination in healthcare workers protects against future infection. METHODS AND ANALYSIS: This is a prospective cohort study design in staff members working in hospitals in the UK. At enrolment, participants are allocated into cohorts, positive or naïve, dependent on their prior SARS-CoV-2 infection status, as measured by standardised SARS-CoV-2 antibody testing on all baseline serum samples and previous SARS-CoV-2 test results. Participants undergo monthly antibody testing and fortnightly viral RNA testing during follow-up and based on these results may move between cohorts. Any results from testing undertaken for other reasons (eg, symptoms, contact tracing) or prior to study entry will also be captured. Individuals complete enrolment and fortnightly questionnaires on exposures, symptoms and vaccination. Follow-up is 12 months from study entry, with an option to extend follow-up to 24 months.The primary outcome of interest is infection with SARS-CoV-2 after previous SARS-CoV-2 infection or COVID-19 vaccination during the study period. Secondary outcomes include incidence and prevalence (both RNA and antibody) of SARS-CoV-2, viral genomics, viral culture, symptom history and antibody/neutralising antibody titres. ETHICS AND DISSEMINATION: The study was approved by the Berkshire Research Ethics Committee, Health Research Authority (IRAS ID 284460, REC reference 20/SC/0230) on 22 May 2020; the vaccine amendment was approved on 12 January 2021. Participants gave informed consent before taking part in the study.Regular reports to national and international expert advisory groups and peer-reviewed publications ensure timely dissemination of findings to inform decision making. TRIAL REGISTRATION NUMBER: ISRCTN11041050.


Subject(s)
COVID-19 , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines , Health Personnel , Humans , Incidence , Multicenter Studies as Topic , Prospective Studies , RNA, Viral , Reinfection , SARS-CoV-2 , United Kingdom/epidemiology , Vaccination
4.
N Engl J Med ; 386(13): 1207-1220, 2022 03 31.
Article in English | MEDLINE | ID: covidwho-1692473

ABSTRACT

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. (Funded by the U.K. Health Security Agency and others; ISRCTN Registry number, ISRCTN11041050.).


Subject(s)
Adaptive Immunity , COVID-19 Vaccines , COVID-19 , SARS-CoV-2 , Adaptive Immunity/immunology , Asymptomatic Diseases , BNT162 Vaccine/therapeutic use , COVID-19/diagnosis , COVID-19/immunology , COVID-19/prevention & control , COVID-19 Nucleic Acid Testing , COVID-19 Vaccines/immunology , COVID-19 Vaccines/therapeutic use , ChAdOx1 nCoV-19/therapeutic use , Health Personnel , Humans , Prospective Studies , United Kingdom , Vaccination/methods , Vaccine Efficacy
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