Там проверяли антитела к коронавирусу у доноров крови или плазмы, которые ранее болели ковидом.
Плазму для лечения ковидных брали у тех переболеших ранее, у кого уровни антител были более 80 УЕ (условных или арбитрарных единиц), ну а серо-положительными считались все, у кого выше 15 УЕ.
(Для сравнения своих данных, и пояснения можно посмотреть еще и тут)
Из переболевших 2723 человек, среднего возраста, начавших участвовать в проекте до 31 марта, 54 человека привились, тк иммунизация в стране началась в январе 2021 (все до этого болели симптмоматично).
Из них до 31 мая 2021 заболели 15 привитых, причем 3 были иммунизированы полностью (14 и более дней после последней дозы вакцины). Заболевание у всех протекало симптоматично, в основном легко и умеренно. Среди оставшихся непривитых доноров, у кого был ранее ковид, до 31 мая заболели 2, асимптоматично (выявили при скрининге на работе). Авторы думают, что может асимптоматичных инфекций было и больше- на работе скринят не везде.
Антитела у всех доноров - были. Впрочем, у тех, кто привился, но заболел, и у тех, кто второй раз заболел без прививки- титры были меньше.
У тех, кто болел ковидом, а спустя время привился, прививка вызвала экспоненциальный рост антител. В разы или даже десятки раз.
Авторы считают, что те, кто болел, не нуждаются в 2 дозах вацины, работает 1, и хорошо, причем не важно, от какой фирмы, и какой тяжести был ранее ковид. Так же, с их точки зрения, лучше иммунный ответ был на прививку у тех, у кого прошло больше времни с момента болезни.
После 100 дней, в среднем, после болезни или иммунизации, уровни антител снижались.
Since January 2021 COVID-19vaccination campaign began in Italy, theimpact of vaccination on antibody levels and suspect vaccine breakthrough infectionsin these subjects were investigated. Post-vaccination anti-Sars-Cov-2 antibody level in 54 previously infected subjects had an exponential increase compared to pre-vaccination level regardless of the number of vaccine doses. However after 100 days from vaccination SARS-CoV-2antibody level tends to decline. Post-vaccination primary infections were detected in 15 cases, with 3 possible breakthrough infections after a full vaccination course. In these cases,antibody response after infection was present but weaker than the one of subjects vaccinated after natural infection.A trend toward stronger antibody response was observed with increasing distance between natural infection and vaccination. Additionally, 2 cases of asymptomatic reinfections are also discussed. All COVID-19convalescent patients that presented for CP donation from the first of April 2020 to the 31stof May 2021 In total 3395 recovered COVID-19patients were tested for anti-SARS-Cov2 antibodies:69.1% were males and 30.9% females, mean age was 40 (range 18-65). Median anti-SARS-CoV-2CLIA result was 46 AU (interquartile range 23-82). Out of these 2723 were recruited before the first of March2021 and were therefore followed up for 4 months and more from diagnosis for possible reinfections. In this group the average follow up was 240 days from diagnosis (range 455-124 days). Overall, by the 31stof May 2021 54 CP donors that were tested for SARS-CoV-2antibodies after primary infection presented for CP or blood donation after 1 or 2 doses of vaccine and were then retested for antibody level. In the 54CP donors pre vaccination CLIA median value was 80AU(AU- Arbitrary Units),range <3.8-283 AU). In all cases after vaccination there was a robust increase in CLIA values: in 45subjects (83%) post vaccination CLIA results were >400 AU, in 8 (15%) they were between 200 and 400 AU , and only one(2%) was between 100 and 200 AU. For18 CP donors whose pre and post-vaccination NA titres wereavailable,the median NA titre increase was eight fold (range 1-64). There was no association between post infection antibody level or the number of doses and antibody response. Overall,from the first of March 2021 to the 31stMay2021, 15 candidate CP donors reported to have been infected after vaccination, 6 females and 9 males, and their mean age was 45 years (range 25-58). In 11 cases COVID-19infection was diagnosed after the first dose of vaccine, in 4 cases after the second dose. Average time from first dose and COVID-19diagnosis was 24days (range 7-71 days). In all cases the infections were symptomatic and classified as mild cases. Average time from diagnosis to antibody test was 43days (range25-66).Median CLIA value was 100 AU (range 12->400), median NA titer on donation was 1:40 (range 1:20 –>1:320). Three cases, two women and one man, were classified as breakthrough infections since they occurred more than 15 days after the second dose: 31, 45 and 50 days respectively. The post infection CLIA results in these cases were 206, 372 and >400 AU respectively. NA titers on donation were 1:40, 1:160, and >1:320 respectively. Out of a cohort of2723 convalescent subjects followed up for more than 4months only two reported microbiologically confirmedre-infection. Both, one girl and one boy, were 26 years old at the time of first diagnosis. The second infection was diagnosed respectively 201 and347 days after the first one In both cases the second infection was asymptomatic and detected during contact tracing in one case androutine occupational screening in the other. Out of the ones that were vaccinated after infection and presented again to blood collection centresfor CP orblood donationwe observedan exponential increase of SARS-CoV-2neutralizing antibody levels compared to post infection levels, regardless of the typeof COVID-19 vaccine,ofthe number of doses and of post-infection antibody levels. In more than80% of cases extremely high CLIA values->400 AU-and NA titres -≥1:320 –were achieved. The median increase of NA waseightfold higher than after natural infection. These data confirm recent published reports that also a single dose of vaccine is able to elicit an robust increase of SARS-CoV-2antibodytitre (6,7)in previously COVID-19infected patients. Our dataadditionallysuggest that a longer interval between infection and vaccination,in our casemore than300 days, is associated to astronger booster effect on antibody levels.Infection after vaccination was not uncommon in convalescent subjects under study,it occurred mainly during the first four weeks after the first dose All of them were symptomatic mild infections and again the SARS-CoV-2antibody level appears to rise when time-lagbetween two events increases. It was observed that novel SARS-CoV-2variants may be associated with breakthrough infections(8,9), we couldn't confirm thisin our study since genetic typing on viral isolates was not available. Reinfection in the population under observation was exceedingly rare: only two cases and both asymptomatic. In both cases SARS-CoV-2antibodies were present after first infection although at a low level. According to a preliminary study ≥80 AU correlate with NA titer≥1:160 (4). Recovered patients with CLIA results ≥80 AU were there invited to donate plasma.