RESUMO
BackgroundStudies using claims databases have reported that SARS-CoV-2 infection >30 days earlier increased the incidence of type 1 diabetes (T1DM). Using exact dates of type 1 diabetes diagnosis from the national register in Scotland linked to virology laboratory data we sought to replicate this finding. MethodsA cohort of 1849411 individuals aged <35 years without diabetes, including all those in Scotland who subsequently tested positive for SARS-CoV-2, was followed from 1 March 2020 to 22 November 2021. Incident T1DM was identified by linkage to the national registry. Cox regression was used to test the association of time-updated infection with incident T1DM. Trends in incidence of T1DM in the total population from 2015-2021 were estimated in a generalized additive model. FindingsThere were 365080 in the cohort with at least one detected SARS-CoV-2 infection during follow-up and 1074 who developed T1DM. The rate ratio for incident T1DM associated with first positive test for SARS-CoV-2 (with no previous infection as reference category) was 0.88 (95% CI 0.63 to 1.23) for infection more than 30 days earlier and 2.62 (95% CI 1.81 to 3.79) for infection in the previous 30 days. However negative and positive SARS-CoV-2 tests were more frequent in the days surrounding T1DM presentation. In those aged 0-14 years incidence of T1DM during 2020-2021 was 20% higher than the 7-year average. InterpretationT1DM incidence in children increased during the pandemic. However the cohort analysis does not support a causal effect of SARS-CoV-2 infection itself on T1DM incidence. FundingNone
RESUMO
BackgroundThe objective of this study was to investigate how protection against COVID-19 conferred by previous infection is modified by vaccination. MethodsIn a cohort of all 152655 individuals in Scotland alive at 90 days after a positive test for SARS-CoV-2 (confirmed by cycle threshold < 30, or two tests) followed till 22 September 2021, rate ratios for reinfection were estimated with calendar time or tests as timescale. FindingsRates of detected and hospitalised reinfection with COVID-19 while unvaccinated were respectively 6.8 (95% CI 6.4 to 7.2) and 0.18 (95% CI 0.12 to 0.25) per 1000 person-months. These rates were respectively 68% and 74% lower than in a matched cohort of individuals who had not previously tested positive. Efficacy of two doses of vaccine in those with previous infection was estimated as as 84% (95 percent CI 81% to 86%) against detected reinfection and 71% (95 percent CI 29% to 88%) against hospitalised or fatal reinfection. The rate of detected reinfection after two doses of vaccine was 1.35 (95% CI 1.02 to 1.78) times higher in those vaccinated before first infection than in those unvaccinated at first infection. InterpretationThe combination of natural infection and vaccination provides maximal protection against new infection with SARS-CoV-2: prior vaccination does not impair this protection. FundingNo specific funding was received for this work. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSIn a recent systematic review of cohort studies reported up to July 2021, the average reduction in COVID-19 infection rates in those with previous infection compared with those without evidence of previous infection was 90%. There is little information about the protective effect of previous infection against severe COVID-19, or about how the protective effects of previous infection against reinfection and severe disease are modified by vaccination. What this paper addsIn unvaccinated individuals the protection against hospitalised COVID-19 conferred by previous infection is similar to that induced by vaccination. In those with previous infection, vaccination reduces the rates of reinfection and hospitalised COVID-19 by about 70%. Implications of all the available evidenceThe combination of natural infection and vaccination provides maximal protection against COVID-19: prior vaccination does not seriously impair this protection.
RESUMO
ObjectivesTo determine whether COVID-19 efficacy varies with clinical risk category and to investigate risk factors for severe COVID-19 in those who have received two doses of vaccine. DesignMatched case-control study (REACT-SCOT). SettingPopulation of Scotland from 1 December 2020 to 8 September 2021. Main outcome measureSevere COVID-19, defined as cases with entry to critical care or fatal outcome. ResultsEfficacy against severe COVID-19 of two doses of vaccine was 94% (95 percent CI 93% to 96%) in those without designated risk conditions, 89% (95 percent CI 86% to 91%) in those with moderate risk conditions, but only 73% (95 percent CI 64% to 79%) in those designated as clinically extremely vulnerable (CEV) and eligible for shielding. Of the 641 cases of severe COVID-19 in double-vaccinated individuals, 47% had moderate risk conditions and 38% were CEV. In the double-vaccinated CEV group, the rate ratio for severe disease (with no risk condition as reference category) was highest in solid organ transplants at 101 (95% CI 47 to 214) but even in this subgroup the absolute risk of severe COVID-19 was low (35 cases in 23678 person-months of follow-up). ConclusionsTwo doses of vaccine protect against severe COVID-19 in CEV individuals but the residual risk in double-vaccinated individuals remains far higher in those who are CEV than in those who are not. These results lay a basis for determining eligibility for additional measures including passive immunization to protect those at highest risk.
RESUMO
BackgroundThe objectives of this study were to investigate whether vaccine efficacy against severe COVID-19 has decreased since Delta became the predominant variant; (2) whether efficacy wanes with time since second dose. MethodsEfficacy was estimated in a matched case-control study that includes all diagnosed cases of COVID-19 in Scotland up to 19 August 2021. The main outcome measure was severe COVID-19, defined as cases with entry to critical care or fatal outcome. FindingsEfficacy of vaccination against severe COVID-19 decreased in May 2021 coinciding with the replacement of the B.1.1.7 (Alpha) by the B.1.617.2 (Delta) variant in Scotland, but this decrease was reversed over the next month. In the most recent time window, the efficacy of two doses was 91% (95 percent CI 87% to 94%) for the AstraZeneca product and 92% (95 percent CI 88% to 95%) for mRNA (Pfizer or Moderna) products. Efficacy of the AstraZeneca product against severe COVID-19 declined with time since second dose to 69% (95 percent CI 52% to 80%) at 20 weeks from second dose. Efficacy of mRNA vaccines declined in the first ten weeks from second dose but more slowly thereafter to 93% (95 percent CI 88% to 96%) at 20 weeks from second dose. InterpretationThese results are reassuring with respect to concerns that efficacy against severe COVID-19 might have fallen since the Delta variant became predominant, or that efficacy of mRNA vaccines wanes with increasing time since second dose. However it is now clear that efficacy of the AstraZeneca vaccine against severe COVID-19 wanes substantially by 20 weeks from second dose, suggesting that delivery of booster doses should initially focus on those who received this type of vaccine. FundingNo specific funding was received for this work. HC is supported by an endowed chair from the AXA Research Foundation. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSSeveral reports have suggested that efficacy of COVID-19 vaccines has fallen since the Delta variant became predominant, or that efficacy wanes with time since second dose. The starting point for this study was the evidence of waning efficacy cited by the CDC, the FDA and more recently the UK Joint Committee on Vaccination and Immunisation in support of their recent recommendations for delivery of booster doses for the general population. Added value of this studyThis study shows that efficacy of both AstraZeneca and mRNA vaccines against severe COVID-19 (fatal or requiring critical care) remains high (around 90%) in the most recent time window, but that efficacy of the AstraZeneca vaccine wanes to about 70% by 20 weeks from second dose. In contrast efficacy of the mRNA vaccines wanes rapidly at first but stabilises at about 90% by 20 weeks from second dose. Implications of all the available evidenceThese results suggest that booster doses of vaccine are not needed for those who have received two doses of mRNA vaccine, except for vulnerable individuals who may require a third primary dose.
RESUMO
BackgroundThe effect of vaccination for COVID-19 on onward transmission is unknown. MethodsA national record linkage study determined documented COVID-19 cases and hospitalisations in unvaccinated household members of vaccinated and unvaccinated healthcare workers from 8th December 2020 to 3rd March 2021. The primary endpoint was COVID-19 14 days following the first dose. ResultsThe cohort comprised of 194,362 household members (mean age 31{middle dot}1 {+/-} 20{middle dot}9 years) and 144,525 healthcare workers (mean age 44{middle dot}4 {+/-} 11{middle dot}4 years). 113,253 (78{middle dot}3%) of healthcare workers received at least one dose of the BNT162b2 mRNA or ChAdOx1 nCoV-19 vaccine and 36,227 (25{middle dot}1%) received a second dose. There were 3,123 and 4,343 documented COVID-19 cases and 175 and 177 COVID-19 hospitalisations in household members of healthcare workers and healthcare workers respectively. Household members of vaccinated healthcare workers had a lower risk of COVID-19 case compared to household members of unvaccinated healthcare worker (rate per 100 person-years 9{middle dot}40 versus 5{middle dot}93; HR 0{middle dot}70, 95% confidence interval [CI] 0{middle dot}63 to 0{middle dot}78). The effect size for COVID-19 hospitalisation was similar, with the confidence interval crossing the null (HR 0{middle dot}77 [95% CI 0{middle dot}53 to 1{middle dot}10]). The rate per 100 person years was lower in vaccinated compared to unvaccinated healthcare workers for documented (20{middle dot}13 versus 8{middle dot}51; HR 0{middle dot}45 [95% CI 0{middle dot}42 to 0{middle dot}49]) and hospitalized COVID-19 (0{middle dot}97 versus 0{middle dot}14; HR 0{middle dot}16 [95% CI 0{middle dot}09 to 0{middle dot}27]). Compared to the period before the first dose, the risk of documented COVID-19 case was lower at [≥] 14 days after the second dose for household members (HR 0{middle dot}46 [95% CI 0{middle dot}30to 0{middle dot}70]) and healthcare workers (HR 0{middle dot}08 [95% CI 0{middle dot}04 to 0{middle dot}17]). InterpretationVaccination of health care workers was associated with a substantial reduction in COVID-19 cases in household contacts consistent with an effect of vaccination on transmission.
RESUMO
ObjectivesTo estimate the real-world effectiveness of the Pfizer/BioNTech BNT162b2 vaccine and Astrazeneca ChAdOx1 vaccine against Confirmed COVID-19, hospitalisations and deaths. To estimate effectiveness on the UK variant of concern. DesignTest negative case control design SettingCommunity COVID-19 PCR testing in England ParticipantsAll adults in England aged 70 years and older (over 7.5 million). All COVID-19 testing in the community among eligible individuals who reported symptoms between 8th December 2020 and 19th February 2021 was included in the analysis. InterventionsOne and two doses of BNT162b2 vaccine. One dose of ChAdOx1 vaccine. Main outcome measuresSymptomatic PCR confirmed SARS-CoV-2 infection, hospitalisations and deaths with COVID-19. ResultsIndividuals aged >=80 years vaccinated with BNT162b2 prior to 4th January, had a higher odds of testing positive in the first 9 days after vaccination (odds ratio up to 1.48, 95%CI 1.23-1.77), indicating that those initially targeted had a higher underlying risk of infection. Vaccine effectiveness was therefore estimated relative to the baseline post-vaccination period. Vaccine effects were noted from 10-13 days after vaccination, reaching an effectiveness of 70% (95% CI 59-78%) from 28-34 days, then plateauing. From 14 days after the second dose a vaccine effectiveness of 89% (95%CI: 85-93%) was seen. Individuals aged >=70 years vaccinated from 4th January had a similar underlying risk of COVID-19 to unvaccinated individuals. With BNT162b2, vaccine effectiveness reached 61% (95%CI 51-69%) from 28-34 days after vaccination then plateaued. With the ChAdOx1 vaccine, vaccine effects were seen from 14-20 days after vaccination reaching an effectiveness of 60% (95%CI 41-73%) from 28-34 days and further increasing to 73% (95%CI 27-90%) from day 35 onwards. On top of the protection against symptomatic disease, cases who had been vaccinated with one dose of BNT162b2 had an additional 43% (95%CI 33-52%) lower risk of emergency hospitalisation and an additional 51% (95%CI 37-62%) lower risk of death. Cases who had been vaccinated with one dose of ChAdOx1 had an additional 37% (95% CI 3-59%) lower risk of emergency hospitalisation. There was insufficient follow-up to assess the effect of ChAdOx1 on mortality due to the later rollout of this vaccine. Combined with the effect against symptomatic disease, this indicates that a single dose of either vaccine is approximately 80% effective at preventing hospitalisation and a single dose of BNT162b2 is 85% effective at preventing death with COVID-19. ConclusionVaccination with either a single dose of BNT162b2 or ChAdOx1 COVID-19 vaccination was associated with a significant reduction in symptomatic SARS-CoV2 positive cases in older adults with even greater protection against severe disease. Both vaccines show similar effects. Protection was maintained for the duration of follow-up (>6 weeks). A second dose of BNT162b2 provides further protection against symptomatic disease but second doses of ChAdOx1 have not yet been rolled out in England. There is a clear effect of the vaccines against the UK variant of concern.
