Ковидные пробои среди привитых в Израиле

[chuka_lis]

Согласно данным работы израильских ученых, проанализировавших заболеваемость ковидом  в июле среди тех, кто привился полностью до июня 2021,  по всем возрастным группам (около 5 млн человек), иммунитет к ковиду со временем затухает, особенно если циркулирует новый штамм.
Затухание иммунитета идет для всех возрастных групп. При этом иммунитет, полученный от прививки, все равно защищает даже спустя 6-7 месяцев от болезни, хоть и не так хорошо как вначале.


Daily Confirmed SARS-CoV-2 Infections and New Cases of Severe Covid-19 among Fully Vaccinated Persons in Israel, June through Early August 2021.  The graph shows increases in the numbers of daily severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and new cases of severe coronavirus disease 2019 (Covid-19), on different scales, during the delta variant wave among persons who had received two doses of vaccine.
В когорте 4.8 млн полностью привитых с января 2021 до начала июня 2021, в июле 2021, когда преимущественно был "дельта" штамм (98% случаев), заболело  примерно 13.5 тысяч человек, из которых у 403 - был тяжелый ковид.
Округленно: среди 2 млн тех, кому от 16 до 39 лет- 5.1 тыс случаев, для 1.5 млн  группы 40-59 лет - 4.6 тыс случаев, для тех, кто старше 60 (около 1.3 млн)- 3.7 тыс случаев ковида.
То есть пропорция заболевших примерно одинаковая, по возрастам.
Среди тех, кто привился в  январе, в июле, в среднем по возрастным группам, заболеваемость была 3.3 человека на 1000 привитых.
Среди тех, кто привился в феврале- 2.2 человека на 1000 привитых
Среди тех, кто привился позже- примерно 1.7-1.5 человек на 1000 привитых.
Однако в том что касается тяжелого ковида- то он был преимущественно у тех, кому за 60.
Среди них, для привитых в январе, июльских случаев тяжелого ковида было 0.34 на 1000, для февраля-0.26,  для марта- 0.15 и для апреля-мая- 0.12 случаев (табл 2).
Для более молодых тенденция та же, но цифры гораздо меньше, тк случаев меньше, чтобы можно было с уверенностью говорить о разнице.
Эффективность вакцины снизилась с 96% для первых двух месяцев после прививки  до 84% спустя 4-7 месяцев после прививки, на фоне "дельты". Потому бустерная прививка- актуальна.

In December 2020, Israel began a mass vaccination campaign against coronavirus disease 2019 (Covid-19) by administering the BNT162b2 vaccine, which led to a sharp curtailing of the outbreak. After a period with almost no cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, a resurgent Covid-19 outbreak began in mid-June 2021. Possible reasons for the resurgence were reduced vaccine effectiveness against the delta (B.1.617.2) variant and waning immunity. The extent of waning immunity of the vaccine against the delta variant in Israel is unclear.We used data on confirmed infection and severe disease collected from an Israeli national database for the period of July 11 to 31, 2021, for all Israeli residents who had been fully vaccinated before June 2021.We defined fully vaccinated persons as those for whom 7 days or more had passed since receipt of the second dose of the BNT162b2 vaccine. We used the Ministry of Health official database that contains all information regarding Covid-19ю Only persons 40 years of age or older were included in the analysis of severe disease because severe disease was rare in the younger population. Severe disease was defined as a resting respiratory rate of more than 30 breaths per minute, oxygen saturation of less than 94% while the person was breathing ambient air, or a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen of less than 300.¹⁴ Persons who died from Covid-19 during the follow-up period were included in the study and categorized as having had severe disease.During the study period, approximately 10% of the detected infections were in residents of Israel returning from abroad. Most residents who traveled abroad had been vaccinated and were exposed to different populations, so their risk of infection differed from that in the rest of the study population. We therefore removed from the analysis all residents who had returned from abroad in July.
Among 5,279,926 fully vaccinated adults, we retained data on 4,791,398 persons for the main analysis
Among these persons, 13,426 had a positive PCR test (confirmed SARS-CoV-2 infection) and 403 had severe Covid-19.
The rate of confirmed SARS-CoV-2 infection showed a clear increase as a function of time from vaccination. Among persons 60 years of age or older who were fully vaccinated in the second half of January, the rate was 3.3 confirmed infections per 1000 persons during the study period, as compared with 2.2 confirmed infections per 1000 persons who became fully vaccinated in the second half of February and 1.7 confirmed infections per 1000 persons fully vaccinated in the second half of March
imilar results were observed in the other age groups and when the analysis was categorized according to age in decades
In this analysis, vaccination periods were defined as January, February, March, and the combined April–May period because of the small numbers of severe cases in each age group. The rate of severe Covid-19 among persons 60 years of age or older who were fully vaccinated in January was 0.34 cases per 1000 persons over the study period and decreased to 0.26 cases per 1000 persons among those who were fully vaccinated in February, 0.15 cases per 1000 persons fully vaccinated in March, and 0.12 cases per 1000 persons fully vaccinated in the April–May period. The numbers of severe cases in the younger age groups were too small for conclusions to be drawn.
A comparison of the rate of confirmed infection among persons vaccinated at different times revealed a clear increase in the rate as the time from vaccination increased in all age groups, with and without correction for measured confounding factors
The rate of severe Covid-19 cases also increased as a function of time from vaccination. Serologic studies in Israel have shown a correlated time-dependent reduction in neutralization titers,^12,20 which might be the biologic mechanism governing the observed waning immunity, and thus support the finding in this population-based research.
In contrast to early findings from the United Kingdom,⁵ approximately two thirds of the cases of severe Covid-19 in Israel during the study period occurred in persons who had received two doses of the BNT162b2 vaccine. Two major differences exist between the studies. First, the current analysis used data from July 2021, a time when, for most of the Israeli population, at least 5 months had passed since receipt of their second dose of vaccine.
A comparison of vaccinated persons with unvaccinated persons is of interest in order to predict the future burden on the health system. We therefore obtained data on the entire Israeli population from the Israeli Central Bureau of Statistics and calculated the number of unvaccinated persons indirectly. Moreover, unvaccinated persons might differ from the vaccinated population in important characteristics that could result in biased estimates. Nevertheless, we estimated the effectiveness of the vaccine against confirmed SARS-CoV-2 infection (see Supplementary Analysis 1). Vaccinated persons were found to be protected even after 6 months, as compared with unvaccinated persons. However, vaccine effectiveness was considerably lower than it had been closer to the vaccination date. Our findings are in line with findings from the randomized trial of the BNT162b2 vaccine, which showed a reduction in vaccine efficacy against symptomatic infection from 96% in the first 2 months after vaccination to 84% at 4 to 7 months after vaccination, when averaged over all age groups combined.
We did not separate the contribution of vaccine breakthrough due to waning immunity from the contribution due to the change in the dominant variant from alpha (B.1.1.7) to delta. Our analysis showed only the clear effect of waning vaccine-induced immunity against the delta variant.