They were found six times more positive than with PCR
Measuring antibodies in saliva is a “useful and easy” strategy to detect covid-19 infections, According to a study by the Barcelona Institute for Global Health (ISGlobal), center promoted by the La Caixa Foundation, and the Sant Joan de Déu Hospital in Barcelona.
In a statement this Thursday, ISGlobal explained that the study, published in ‘BMC Medicine’, has followed more than 1,500 children and 400 adults who attended ‘casals’ or summer camps in Barcelona last year, from whom two saliva samples were taken: at the beginning and at the end of the ‘casal’.
The project sought “sensitive and minimally invasive” antibody detection techniques, that were able to detect low levels of antibodies and that they could be carried out with a certain frequency.
The results indicate that 3.2% of the participants developed antibodies between the two samples, This “reflects new infections” at a rate six times higher than that estimated by the PCRs performed each week.
“It has been seen that some minors can be positive for antibodies despite being negative by PCR, which suggests that the child population is capable of generating an immune response that prevents the infection from establishing, “said the leader of the study, Carlota Dobaño.
This may also be because asymptomatic children have lower viral loads or shed the virus more quickly.
Likewise, the analysis shows that the percentage of new infections was higher in the adult population (2.94%) than in the child (1.3%), which suggests differences in the dynamics of infection and viral transmission.
Finally, contrary to what has been seen in blood, asymptomatic people had higher levels of ‘anti-Spike’ antibodies in saliva, which suggests a protective role of said antibodies in respiratory mucosa.
This means that the said antibodies “could be used to measure the protective immunity generated after vaccination, particularly in the case of intranasal vaccines, “said study senior co-author Gemma Moncunill.