Vaccination of healthcare workers: 'four vaccines, four VOCs'. A comparative study of antibody production by 4 different SARS-CoV-2 vaccines against the different VOCs in healthcare workers.

The coronavirus (SARS-CoV-2) has changed since the first time the virus arrived in the Netherlands. New variants of the virus can more easily break through the protection of vaccinations or immunity from previous infections. It is therefore very important to know how the four vaccines used in the Netherlands perform against virus variants that we currently know, in order to prepare ourselves as best as possible for the future. That is why we determined the immunity (amount of antibodies) in 165 hospital employees. These people had previously been vaccinated with one of the four corona vaccines (BNT162b2 (Pfizer), mRNA-1273 (Moderna), AZD1222 (AstraZeneca) or Ad26.COV2.S (Janssen)). These employees had not previously experienced a corona infection. The results showed that the level of protective (neutralizing) antibodies was highest in subjects vaccinated with mRNA-1273 (Moderna), followed by subjects vaccinated with BNT162b2 (Pfizer). Persons vaccinated with AZD1222 (Astra Zeneca) or Ad26.COV2.S (Janssen) had the lowest numbers of antibodies. The antibodies had a much less neutralizing effect against the new Omicron variant than against the original coronavirus. If these people subsequently received a booster vaccination with BNT162b2 (Pfizer), the antibodies clearly increased, even when it comes to new variants such as Omicron. What was striking is that the effect of the booster vaccination was the least good in people who were originally vaccinated with AZD1222 (Astra Zeneca).