Эффективность вакцины в Англии

chuka_lis — 11.09.2021 Ученые проанализирваоли заболеваемость среди молодежи и привитых жителей острова  до 65 лет, в последнюю ковидную волну, когда господствовал вариант "дельта", и пришли к выводу, что с приходом этого штамма рост инфекций  шел экспоненциально (с мая по июль),  и не только среди непривитых (то есть молодежи возрастом 13-17 лет, в 9 раз),  но и среди тех, кто поулчил обе дозы вакцины (рост в 3 раза), увы.
Летом у них среди всех подхвативших ковид  - 44% были полностью привиты.
Согласно оценкам авторов работы, взвешенная эфективность вакцины против инфекции для привитых возрастом 18-64 года составляла 49% (но если считать только высокую вирусную нагрузку, менее 27 циклов ПЦР в тест-образце, то  эффективность  можно оценить как 58%). Защиту прививки от симптоматического ковида (когда минимум 1 из трех классических симптомов уже был на момент теста) определили в 59%.
Авторы предупреждают, что исходя из таких оценок, не смотря на выскоий уровень привитости в стране, можно ожидать следующей вспышки осенью, даже от той же дельты.

We analysed prevalence trends and their drivers using reverse transcription-polymerase chain reaction (RT-PCR) swab-positivity data from round 12 (between 20 May and 7 June 2021) and round 13 (between 24 June and 12 July 2021) of the Real-time Assessment of Community Transmission-1 (REACT-1) study, with swabs sent to non-overlapping random samples of the population ages 5 years and over in England. Results We observed sustained exponential growth with an average doubling time in round 13 of 25 days (lower Credible Interval of 15 days) and an increase in average prevalence from 0.15% (0.12%, 0.18%) in round 12 to 0.63% (0.57%, 0.18%) in round 13. The rapid growth across and within rounds appears to have been driven by complete replacement of Alpha variant by Delta, and by the high prevalence in younger less-vaccinated age groups, with a nine-fold increase between rounds 12 and 13 among those aged 13 to 17 years. Prevalence among those who reported being unvaccinated was three-fold higher than those who reported being fully vaccinated. However, in round 13, 44% of infections occurred in fully vaccinated individuals, reflecting imperfect vaccine effectiveness against infection despite high overall levels of vaccination. Using self-reported vaccination status, we estimated adjusted vaccine effectiveness against infection in round 13 of 49% (22%, 67%) among participants aged 18 to 64 years, which rose to 58% (33%, 73%) when considering only strong positives (Cycle threshold [Ct] values < 27); also, we estimated adjusted vaccine effectiveness against symptomatic infection of 59% (23%, 78%), with any one of three common COVID-19 symptoms reported in the month prior to swabbing. Sex (round 13 only), ethnicity, household size and local levels of deprivation jointly contributed to the risk of higher prevalence of swab-positivity.
From end May to beginning July 2021 in England, where there has been a highly successful vaccination campaign with high vaccine uptake, infections were increasing exponentially driven by the Delta variant and high infection prevalence among younger, unvaccinated individuals despite double vaccination continuing to effectively reduce transmission. Although slower growth or declining prevalence may be observed during the summer in the northern hemisphere, increased mixing during the autumn in the presence of the Delta variant may lead to renewed growth, even at high levels of vaccination.

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