The US immunologist’s statements on the Delta variant are being discussed: “The level of virus in vaccinated who become infected, a rare event, is identical in unvaccinated”
“Now we are dealing with a different virus,” he said Anthony Fauci, chief medical advisor to the White House, referring to the Delta variantof the coronavirus and the decision of the Centers for Disease Control and Prevention (CDC) on the recommendation to wear masks by vaccinates.
“This is not the original virus. It has much more efficient capabilities in person-to-person transmission “, added Fauci, reiterating the increased contagiousness of the variant and explained:” The Delta can also infect people who have been vaccinated and these can in turn transmit the virus to others ».
The CDC on Tuesday recommended that fully vaccinated people return to wearing masks indoors in places where there are high transmission rates (in the US, counties that have over 50 cases per 100,000 residents in a seven-day period). Delta is now the dominant strain in the United States, as in hundreds of other countries in the world and its race does not stop thanks to its ability to infect between 40 and 60% higher than the Alfa, which in turn was 50% more infectious than the original Wuhan strain of SARS-CoV-2.
With about half of Americans not yet vaccinated, there are two pandemics at different speeds in the US: Fauci reiterated that «it is necessary for the majority of people to get vaccinated. If we reach 85-90% of the vaccinated population, the Delta variant would not have many places to go and would eventually disappear ». CDC officials have been persuaded to the new order “by new scientific evidence showing that even vaccinated people can be infected and can carry the virus in large quantities,” writes the New York Times quoting the opinion of Dr. Rochelle P. Walensky, director of the CDC, who added: “On rare occasions, some vaccinated people infected with a Delta variant can be contagious and spread the virus to others.”
Finally, Fauci in a video on YouTube summarized the state of knowledge by recalling that, with complete vaccination, they drop: the chance to get infected, of transmit the contagion, to go to the hospital and die.
How contagious is a vaccine infected with the Delta variant? It is still not entirely clear: the data are few and mostly come from the United Kingdom where the Delta has been dominant for a long time and the analyzes have started longer.
The variable contagiousness of a vaccine does not depend only on the effectiveness of the vaccine Received: Vaccine efficacy measures the individual’s protection from getting the virus. In Italy it is estimated that it is 88.5% for the totally vaccinated. The latest English data speak of a protection (with 2 doses) from 65 to 90%. Think of a closed environment with one or more positives: if those present are all vaccinated, 35 out of 100 are infected in the worst case. Vaccines prevent infection. Non-infected individuals cannot transmit; therefore, vaccines are also effective in preventing transmission. There protection is high but not total: we know that you can get sick again, but also that Covid disease will be (in almost all cases) mild.
What does it mean? That even when the vaccine is positive it transmits less viruses? Yes, it can be understood from the data on infections, which however are empirical. There are no specific studies on the transmission (usually in the family) between a positive vaccinee and another person on the Delta. There are also no studies on viral loads, which are even more difficult to do. There are however regarding the Alfa variant. They have shown that the chances of a vaccine being infected are very low. The vaccinated people do not get infected in the same way and in most cases they have no symptoms. This means that the viral load is low and there is a lower chance of infecting others. If the amount of virus that replicates decreases, its circulation also decreases a lot. A domestic transmission study in England found that family contacts of cases vaccinated with a single dose had an approximately 40-50% reduced risk of becoming infected. The study was published in the scientific journal New England Journal of Medicine NEJM (one of the most prestigious) coordinated by scientists from the British public service (PHE), but related to the Alfa variant, because it was held until 28 February.
Similar studies have also been conducted in the US and Israel: again on the NEJM, the CDC published a research carried out from 14 December 2020 to 10 April 2021 on 3,975 healthcare professionals. One was encountered 40% lower average viral load in positive vaccinated subjects. The risk of feverish symptoms it was 58% shorter and the shorter duration of illness was 2-3 days shorter in bed. The vaccines attenuated the viral load, the risk of febrile symptoms and the duration of the disease. A study conducted in February in Israel (not yet published) analyzed people who tested positive for the SARS-CoV-2 test after inoculation with the Pfizer vaccine: viral load was reduced by 4 times for infections that occurred 12-28 days after the first dose of vaccine.
These are studies on the Alpha variant, but they lead us to believe that, even considering the greater contagiousness of the Delta, the vaccinated are first of all protected from contagion (between 65 and 90%) and, even if infected, they host a reduced viral load that lowers strongly the chances of infecting.
What are the contagion variables that remain to be calculated? If I am vaccinated in a room who contracted the virus, however I am less infectious than someone who contracted the virus without being vaccinated. More: if I am in an indoor room, my minimum infectious capacity will be practically nil against a vaccinated who in turn is protected from contagion (more or less depending on the doses he has done and the vaccine he has done ). Basically there are two shields that protect us. If I meet an unvaccinated person I am “not very contagious”, but he hasn’t protection shields and is totally susceptible to my virus.
July 29, 2021 (change July 29, 2021 | 13:55)
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