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Vaccine-induced and naturally-acquired protection against Omicron and Delta symptomatic infection and severe COVID-19 outcomes, France, December 2021 to January 2022
More LessWe assessed the protection conferred by naturally-acquired, vaccine-induced and hybrid immunity during the concomitant Omicron and Delta epidemic waves in France on symptomatic infection and severe COVID-19. The greatest levels of protection against both variants were provided by hybrid immunity. Protection against Omicron symptomatic infections was systematically lower and waned at higher speed than against Delta in those vaccinated. In contrast, there were little differences in variant-specific protection against severe inpatient outcomes in symptomatic individuals.
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Immediate side effects of Comirnaty COVID-19 vaccine: A nationwide survey of vaccinated people in Israel, December 2020 to March 2021
BackgroundCOVID-19 vaccine safety is of major interest worldwide, since there is no prior experience with it. Israel was one of the first countries to widely use the Comirnaty vaccine.
AimWe aimed to assess the vaccine's short-term side effects directly from a large population and to predict influencing factors for self-reporting side effects.
MethodsIn a retrospective cohort study, we investigated self-reported systemic vaccine side-effects using electronic surveys sent to vaccinated individuals between 20 December 2020 and 11 March 2021, within 3 days following administration of the first and second dose. We determined predictors for reporting systemic side effects by logistic regression.
ResultsA total of 1,213,693 patients received at least one vaccine dose and 301,537 (24.8%) answered at least one survey. Among them, 68,162 (30.4%) and 89,854 (59.9%) individuals filled the first and the second dose surveys, respectively, and reported one or more side effects. Most common side effects were fatigue, headache and myalgia. Several respondents reported facial paraesthesia after first and second dose, respectively (n = 1,675; 0.7% and n = 1,601; 1.1%). Individuals younger than 40 years and women reported side effects more frequently than others, but pregnant women reported less. Pregnancy was a weak predictor for reporting any side effect in general and in particular fatigue, myalgia, headache, chills and fever.
ConclusionsWe found further support for minor short-term side effects, within 3 days of receiving the Comirnaty vaccine. These findings from vaccine recipients in general and pregnant women in particular can improve vaccine acceptance.
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Risk reduction of severe outcomes in vaccinated COVID-19 cases: an analysis of surveillance data from Estonia, Ireland, Luxembourg and Slovakia, January to November 2021
Despite high COVID-19 vaccine coverage in the EU/EEA, there are increasing reports of SARS-CoV-2 infections and hospitalisations in vaccinated individuals. Using surveillance data from Estonia, Ireland, Luxembourg and Slovakia (January–November 2021), we estimated risk reduction of severe outcomes in vaccinated cases. Increasing age remains the most important driver of severity, and vaccination significantly reduces risk in all ages for hospitalisation (adjusted relative risk (aRR): 0.32; 95% confidence interval (CI): 0.26–0.39) and death (aRR: 0.20; 95% CI: 0.13–0.29).
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Investigation of outbreak cases infected with the SARS-CoV-2 B.1.640 variant in a fully vaccinated elderly population, Normandy, France, November to December 2021
Three confirmed infections with the SARS-CoV-2 B.1.640 variant under monitoring were reported in Normandy, north-western France in late November 2021. Investigations led to the identification of two events linked to the same cluster. A total of 75 confirmed and probable B.1.640 cases were reported. All had completed the primary vaccination series. Sixty-two cases were older than 65 years. Fifty-six cases had symptoms and four were hospitalised. This investigation provides preliminary results concerning a variant with limited information currently available.
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Waning antibody levels after COVID-19 vaccination with mRNA Comirnaty and inactivated CoronaVac vaccines in blood donors, Hong Kong, April 2020 to October 2021
The mRNA vaccine Comirnaty and the inactivated vaccine CoronaVac are both available in Hong Kong’s COVID-19 vaccination programme. We observed waning antibody levels in 850 fully vaccinated (at least 14 days passed after second dose) blood donors using ELISA and surrogate virus neutralisation test. The Comirnaty-vaccinated group’s (n = 593) antibody levels remained over the ELISA and sVNT positive cut-offs within the first 6 months. The CoronaVac-vaccinated group’s (n = 257) median antibody levels began to fall below the cut-offs 4 months after vaccination.
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Impact of booster vaccination on the control of COVID-19 Delta wave in the context of waning immunity: application to France in the winter 2021/22
Europe has experienced a large COVID-19 wave caused by the Delta variant in winter 2021/22. Using mathematical models applied to Metropolitan France, we find that boosters administered to ≥ 65, ≥ 50 or ≥ 18 year-olds may reduce the hospitalisation peak by 25%, 36% and 43% respectively, with a delay of 5 months between second and third dose. A 10% reduction in transmission rates might further reduce it by 41%, indicating that even small increases in protective behaviours may be critical to mitigate the wave.
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Serological responses to COVID-19 Comirnaty booster vaccine, London, United Kingdom, September to December 2021
Serum samples were collected pre- and post-booster vaccination with Comirnaty in 626 participants (aged ≥ 50 years) who had received two Comirnaty doses < 30 days apart, two Comirnaty doses ≥ 30 days apart or two Vaxzevria doses ≥ 30 days apart. Irrespective of primary vaccine type or schedule, spike antibody GMTs peaked 2–4 weeks after second dose, fell significantly ≤ 38 weeks later and rose above primary immunisation GMTs 2–4 weeks post-booster. Higher post-booster responses were observed with a longer interval between primary immunisation and boosting.
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Vaccine effectiveness against severe acute respiratory infections (SARI) COVID-19 hospitalisations estimated from real-world surveillance data, Slovenia, October 2021
We estimated vaccine effectiveness (VE) against severe COVID-19 during October 2021, using Slovenian surveillance data. For people fully vaccinated with any vaccine in age groups 18–49, 50–64, ≥ 65 years, VE was 86% (95% CI: 79–90), 89% (85–91), and 77% (74–81). Among ≥ 65 year-olds fully vaccinated with mRNA vaccines, VE decreased from 93% (95% CI: 88–96) in those vaccinated ≤ 3 months ago to 43% (95% CI: 30–54) in those vaccinated ≥ 6 months ago, suggesting the need for early boosters.
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Increasing risk of breakthrough COVID-19 in outbreaks with high attack rates in European long-term care facilities, July to October 2021
Carl Suetens , Pete Kinross , Pilar Gallego Berciano , Virginia Arroyo Nebreda , Eline Hassan , Clémentine Calba , Eugenia Fernandes , Andre Peralta-Santos , Pedro Casaca , Nathalie Shodu , Sara Dequeker , Flora Kontopidou , Lamprini Pappa , Oliver Kacelnik , Anita Wang Børseth , Lois O’Connor , Patricia Garvey , Rasa Liausedienė , Rolanda Valintelienė , Corinna Ernst , Joël Mossong , Mária Štefkovičová , Zuzana Prostináková , Ann Caroline Danielsen , Aikaterini Mougkou , Favelle Lamb , Orlando Cenciarelli , Dominique L. Monnet and Diamantis PlachourasWe collected data from 10 EU/EEA countries on 240 COVID-19 outbreaks occurring from July−October 2021 in long-term care facilities with high vaccination coverage. Among 17,268 residents, 3,832 (22.2%) COVID-19 cases were reported. Median attack rate was 18.9% (country range: 2.8–52.4%), 17.4% of cases were hospitalised, 10.2% died. In fully vaccinated residents, adjusted relative risk for COVID-19 increased with outbreak attack rate. Findings highlight the importance of early outbreak detection and rapid containment through effective infection prevention and control measures.
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Initial assessment of the COVID-19 vaccination’s impact on case numbers, hospitalisations and deaths in people aged 80 years and older, 15 EU/EEA countries, December 2020 to May 2021
Nathalie Nicolay , Francesco Innocenti , Julien Beauté , Veronika Učakar , Marta Grgič Vitek , Eero Poukka , Tuula Hannila-Handelberg , Charmaine Gauci , Tanya Melillo , Theano Georgakopoulou , Jiri Jarkovsky , Pavel Slezak , Concepción Delgado-Sanz , Carmen Olmedo-Lucerón , Heleene Suija , Rasa Liausediene , Piaras O’Lorcain , Niamh Murphy , André Peralta-Santos , Pedro Casaca , Ioanna Gregoriou , Nick Bundle , Gianfranco Spiteri and Giovanni RavasiPrioritisation of elderly people in COVID-19 vaccination campaigns aimed at reducing severe outcomes in this group. Using EU/EEA surveillance and vaccination uptake, we estimated the risk ratio of case, hospitalisation and death notifications in people 80 years and older compared with 25–59-year-olds. Highest impact was observed for full vaccination uptake 80% or higher with reductions in notification rates of cases up to 65% (IRR: 0.35; 95% CI: 0.13–0.99), hospitalisations up to 78% (IRR: 0.22; 95% CI: 0.13–0.37) and deaths up to 84% (IRR: 0.16; 95% CI: 0.13–0.20).
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Estimated number of deaths directly averted in people 60 years and older as a result of COVID-19 vaccination in the WHO European Region, December 2020 to November 2021
Margaux MI Meslé , Jeremy Brown , Piers Mook , José Hagan , Roberta Pastore , Nick Bundle , Gianfranco Spiteri , Giovanni Ravasi , Nathalie Nicolay , Nick Andrews , Tetiana Dykhanovska , Joël Mossong , Małgorzata Sadkowska-Todys , Raina Nikiforova , Flavia Riccardo , Hinta Meijerink , Clara Mazagatos , Jan Kyncl , Jim McMenamin , Tanya Melillo , Stella Kaoustou , Daniel Lévy-Bruhl , Freek Haarhuis , Rivka Rich , Meaghan Kall , Dorit Nitzan , Catherine Smallwood and Richard G PebodySince December 2019, over 1.5 million SARS-CoV-2-related fatalities have been recorded in the World Health Organization European Region - 90.2% in people ≥ 60 years. We calculated lives saved in this age group by COVID-19 vaccination in 33 countries from December 2020 to November 2021, using weekly reported deaths and vaccination coverage. We estimated that vaccination averted 469,186 deaths (51% of 911,302 expected deaths; sensitivity range: 129,851–733,744; 23–62%). Impact by country ranged 6–93%, largest when implementation was early.
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Estimating averted COVID-19 cases, hospitalisations, intensive care unit admissions and deaths by COVID-19 vaccination, Italy, January−September 2021
We assessed the impact of COVID-19 vaccination in Italy, by estimating numbers of averted COVID-19 cases, hospitalisations, ICU admissions and deaths between January and September 2021, by age group and geographical macro areas. Timing and speed of vaccination programme implementation varied slightly between geographical areas, particularly for older adults. We estimated that 445,193 (17% of expected; range: 331,059−616,054) cases, 79,152 (32%; range: 53,209−148,756) hospitalisations, 9,839 ICU admissions (29%; range: 6,434−16,276) and 22,067 (38%; range: 13,571−48,026) deaths were prevented by vaccination.
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Changes in COVID-19 outbreak severity and duration in long-term care facilities following vaccine introduction, England, November 2020 to June 2021
We describe the impact of changing epidemiology and vaccine introduction on characteristics of COVID-19 outbreaks in 330 long-term care facilities (LTCF) in England between November 2020 and June 2021. As vaccine coverage in LTCF increased and national incidence declined, the total number of outbreaks and outbreak severity decreased across the LTCF. The number of infected cases per outbreak decreased by 80.6%, while the proportion of outbreaks affecting staff only increased. Our study supports findings of vaccine effectiveness in LTCF.
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The SARS-CoV-2 Lambda variant and its neutralisation efficiency following vaccination with Comirnaty, Israel, April to June 2021
Neta Zuckerman , Ital Nemet , Limor Kliker , Nofar Atari , Yaniv Lustig , Efrat Bucris , Dana Bar Ilan , Miranda Geva , Reut Sorek-Abramovich , Chen Weiner , Nir Rainy , Adina Bar-Chaim , Patricia Benveniste-Levkovitz , Ramzia Abu Hamed , Gili Regev-Yochay , Ofra Hevkin , Orna Mor , Sharon Alroy-Preis , Ella Mendelson and Michal MandelboimThe SARS-CoV-2 Lambda (Pango lineage designation C.37) variant of interest, initially identified in Peru, has spread to additional countries. First detected in Israel in April 2021 following importations from Argentina and several European countries, the Lambda variant infected 18 individuals belonging to two main transmission chains without further spread. Micro-neutralisation assays following Comirnaty (BNT162b2 mRNA, BioNTech-Pfizer) vaccination demonstrated a significant 1.6-fold reduction in neutralising titres compared with the wild type virus, suggesting increased susceptibility of vaccinated individuals to infection.
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Vaccine effectiveness against SARS-CoV-2 transmission to household contacts during dominance of Delta variant (B.1.617.2), the Netherlands, August to September 2021
We estimated SARS-CoV-2 vaccine effectiveness against onward transmission by comparing secondary attack rates among household members for vaccinated and unvaccinated index cases, based on source and contact tracing data collected when the Delta variant was dominant. Effectiveness of full vaccination of the index case against transmission to unvaccinated and fully vaccinated household contacts, respectively, was 63% (95% confidence interval (CI): 46–75) and 40% (95% CI: 20–54), in addition to the direct protection of vaccination of contacts against infection.
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Seroprevalence of anti-SARS-CoV-2 antibodies 6 months into the vaccination campaign in Geneva, Switzerland, 1 June to 7 July 2021
Silvia Stringhini , María-Eugenia Zaballa , Nick Pullen , Javier Perez-Saez , Carlos de Mestral , Andrea Jutta Loizeau , Julien Lamour , Francesco Pennacchio , Ania Wisniak , Roxane Dumont , Hélène Baysson , Viviane Richard , Elsa Lorthe , Claire Semaani , Jean-François Balavoine , Didier Pittet , Nicolas Vuilleumier , François Chappuis , Omar Kherad , Andrew S. Azman , Klara Posfay-Barbe , Laurent Kaiser , Idris Guessous and on behalf of the Specchio-COVID19 study groupBackgroundUp-to-date seroprevalence estimates are critical to describe the SARS-CoV-2 immune landscape and to guide public health decisions.
AimWe estimate seroprevalence of anti-SARS-CoV-2 antibodies 15 months into the COVID-19 pandemic and 6 months into the vaccination campaign.
MethodsWe conducted a population-based cross-sectional serosurvey between 1 June and 7 July 2021, recruiting participants from age- and sex-stratified random samples of the general population. We tested participants for anti-SARS-CoV-2 antibodies targeting the spike (S) or nucleocapsid (N) proteins using the Roche Elecsys immunoassays. We estimated the anti-SARS-CoV-2 antibodies seroprevalence following vaccination and/or infection (anti-S antibodies), or infection only (anti-N antibodies).
ResultsAmong 3,355 individuals (54.1% women; 20.8% aged < 18 years and 13.4% aged ≥ 65 years), 2,161 (64.4%) had anti-S antibodies and 906 (27.0%) had anti-N antibodies. The total seroprevalence was 66.1% (95% credible interval (CrI): 64.1–68.0). We estimated that 29.9% (95% Crl: 28.0–31.9) of the population developed antibodies after infection; the rest having developed antibodies via vaccination. Seroprevalence estimates differed markedly across age groups, being lowest among children aged 0–5 years (20.8%; 95% Crl: 15.5–26.7) and highest among older adults aged ≥ 75 years (93.1%; 95% Crl: 89.6–96.0). Seroprevalence of antibodies developed via infection and/or vaccination was higher among participants with higher educational level.
ConclusionMost of the population has developed anti-SARS-CoV-2 antibodies, despite most teenagers and children remaining vulnerable to infection. As the SARS-CoV-2 Delta variant spreads and vaccination rates stagnate, efforts are needed to address vaccine hesitancy, particularly among younger individuals and to minimise spread among children.
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Effectiveness of COVID-19 vaccines against SARS-CoV-2 infection with the Delta (B.1.617.2) variant: second interim results of a living systematic review and meta-analysis, 1 January to 25 August 2021
The Delta variant has become the dominant strain of SARS-CoV-2. We summarised the evidence on COVID-19 vaccine effectiveness (VE) identified in 17 studies that investigated VE against different endpoints. Pooled VE was 63.1% (95% confidence interval (CI): 40.9–76.9) against asymptomatic infection, 75.7% (95% CI: 69.3–80.8) against symptomatic infection and 90.9% (95% CI: 84.5–94.7) against hospitalisation. Compared with the Alpha variant, VE against mild outcomes was reduced by 10–20%, but fully maintained against severe COVID-19.
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Long time frames to detect the impact of changing COVID-19 measures, Canada, March to July 2020
BackgroundMany countries have implemented population-wide interventions to control COVID-19, with varying extent and success. Many jurisdictions have moved to relax measures, while others have intensified efforts to reduce transmission.
AimWe aimed to determine the time frame between a population-level change in COVID-19 measures and its impact on the number of cases.
MethodsWe examined how long it takes for there to be a substantial difference between the number of cases that occur following a change in COVID-19 physical distancing measures and those that would have occurred at baseline. We then examined how long it takes to observe this difference, given delays and noise in reported cases. We used a susceptible-exposed-infectious-removed (SEIR)-type model and publicly available data from British Columbia, Canada, collected between March and July 2020.
ResultsIt takes 10 days or more before we expect a substantial difference in the number of cases following a change in COVID-19 control measures, but 20–26 days to detect the impact of the change in reported data. The time frames are longer for smaller changes in control measures and are impacted by testing and reporting processes, with delays reaching ≥ 30 days.
ConclusionThe time until a change in control measures has an observed impact is longer than the mean incubation period of COVID-19 and the commonly used 14-day time period. Policymakers and practitioners should consider this when assessing the impact of policy changes. Rapid, consistent and real-time COVID-19 surveillance is important to minimise these time frames.
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Nosocomial outbreak caused by the SARS-CoV-2 Delta variant in a highly vaccinated population, Israel, July 2021
More LessA nosocomial outbreak of SARS-CoV-2 Delta variant infected 42 patients, staff and family members; 39 were fully vaccinated. The attack rate was 10.6% (16/151) among exposed staff and reached 23.7% (23/97) among exposed patients in a highly vaccinated population, 16–26 weeks after vaccination (median: 25 weeks). All cases were linked and traced to one patient. Several transmissions occurred between individuals wearing face masks. Fourteen of 23 patients became severely sick or died, raising a question about possible waning immunity.
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