Salut, Covid-19, Vacunes
There is a message circulating in WhatsApp these weeks ensuring that people, even vaccinated, run the risk of being “major contagious agents”, that is, that are susceptible of continuing infecting others, and they will have to be vaccinated more frequently. This is FALSE. The studies performed to date only speak about the capacity of the vaccine against covid-19 to develop the most severe cases. There is also evidence that after receiving the vaccine, a person can continue infecting, but no study mentions the existence of specific groups that should receive the vaccine more often than the others due to a transmissibility issue.
"Even if you get vaccinated, you can become a superspreader and you will have to get vaccinated again and again"
At the beginning of the SARS-CoV-2 pandemic the figure of the superspreader was largely debated, as in some pre-prints (research non-validated by the scientific community) and studies it had been observed that the 80% of transmissions could be produced by the 20% of the individuals, although not many information was provided about the specific characteristics of the alleged superspreaders. A recent study from Tulane and Harvard universities has observed that there exists a correlation between obesity, age and covid-19 infection and the propensity to exhale more respiratory drops (and thus, be more susceptible to transmitting the virus).
The viral text does not clarify whether it really refers to superspreaders or whether it simply highlights that the vaccine does not prevent someone from remaining contagious with the same viral load as they would have without having received the injection. In any case, and as Adelaida Sarukhan, immunologist and scientific writer at the Institute of Global Health in Barcelona (ISGlobal in Catalan), explains to Verificat, “the clinical trials of the vaccines were designed with the main goal of evaluating if they could protect against symptomatic infections, not to know if they reduced asymptomatic infections”. Hence, the expert continues, “it is still early to certainly know whether vaccines only protect from the disease or they also protect from the infection (thus reducing transmissibility).
Recent studies have analysed the infections of vaccinated people and it has been observed that, when they get infected, they present a much lower viral load. “This suggests that vaccinated people, although they can get infected, are less contagious”. Hence, the probability for a vaccinated person to be a major contagious agent is very low”, points the immunologist. Up to now, real life studies point that, to a greater or lesser extent, vaccines prevent [as well] the infection without symptoms”, points out José Antonio Navarro-Alonso, specialised in pediatric medicine, expert in covid-19 vaccination and one of the funder members of the Spanish Association of Vaccinology (AEV). This means that “they can avoid the virus replication (less infectiousness), thus its dissemination to the contacts of the vaccinated person (less contagiousness) and, ultimately contribute to the emergence of a community protection',' he concludes.
One of the first studies (data not yet published in a paper) on transmission from infected people, vaccinated or not, to other people (in this case, cohabitants) has just been published in the UK and found that the probability of an infected but vaccinated person —both with the Pfizer and AstraZeneca injection— infecting a cohabitant is 40-50% lower compared to an infected but unvaccinated person: "That is, vaccines could reduce transmission by half," Sarukhan concludes.
In the message it is also assumed that even if you have received the vaccine you will have to get vaccinated “again and again” because “even if you get vaccinated, you can be a major infectious agent”
This is false: the frequency at which we must acquire the booster dose will not be determined by transmissibility, but for the duration of immunity. For the moment, some ongoing studies have already ensured that some vaccines, such as Pfizer’s, generate an immunity that lasts at least for 6 months. For the moment, there is no specific data because not enough time has passed, but there are examples for other types of vaccines, such as hepatitis B, which offers protection up to 12 years.
Aquest article és part del projecte "Les Mentides Amenacen la Salut", el primer portal de fact-checking de rumors sobre la covid-19 de Catalunya.