The first vaccine dose reduces covid-19 cases in Catalan care homes

BarcelonaThe effect of the vaccines administered in the care homes of Catalonia is beginning to be noticed, according to an exploratory analysis of the Department of Health, which has made a follow-up of both residents and workers who are vaccinated. The monitoring has been done since the vaccination campaign began on 27 December until 17 January, and has measured the protective effect of the first dose of the vaccine.

To carry out the analysis, the cases of 36,562 residents who were not vaccinated and had not had covid-19 previously were studied. Of these residents, 29,332 were vaccinated at different times during the follow-up. In the first 24 days after starting the vaccination campaign, 1,506 infections were found among the unvaccinated and 686 among the vaccinated. In addition, the rate in the first 12 days among vaccinated people was of 1.58 cases per day per 1,000 people, while between days 13 and 24 this rate has been reduced to 1.25. The conclusions, which -as the Health Department warns- are preliminary, indicate a 21% decrease in the rate of occurrence of cases among vaccinated people as time passes, more specifically from days 10 or 12, after the first dose.

The same analysis has been done with a group of professionals working in care homes. In this case, 32,278 unvaccinated professionals who had not had the disease were monitored, of whom 19,995 were vaccinated during the follow-up. In the first 24 days after starting the vaccination, 1,019 cases were observed among those who had not yet been vaccinated and 301 among those who had received the injection. From these observations, the Health Departmenthas calculated that the rate of cases in the first 12 days in vaccinated people was of 1.15 cases per 1,000 people, while between days 13 and 24 the rate dropped to 0.66 cases. This means that the rate of occurrence of cases among vaccinated people has been reduced by 43% from days 10 or 12.

Although the results are encouraging, the Health Department warns that this is a preliminary study that has limitations that have to be controlled in subsequent analyses. This work, motivated by the fact that clinical trials indicated that from 10 days after the first dose the protective effects of the vaccine began to be noticed, has been developed by the team of the Information System of Primary Care Services (SISAP) of the Catalan Institute of Health.