Chinese vaccines: differences and similarities between Sinovac and Sinopharm

Sinovac and Sinopharm they look very similar, but they are not exactly the same. The names refer to Chinese laboratories producing vaccines against Covid-19, widely used in South America. The first was applied en masse in Chile, while the second has two million doses distributed in Argentina and there are still two million more from the contract made by the Argentine government of the next arrival. Although both originate from inactivated viruses (that is, the genetic material is destroyed and cannot be reproduced in the body), they have not shown identical results in what is known from clinical trials. as well as the efficacy demonstrated in Chile: a A study conducted by researchers at the University of Chile concluded that with one dose, only 3% is obtained to avoid the symptoms of covid. Perhaps this, combined with the early lifting of restrictions and mobility, has generated an increase in cases that have left the Trans-Andean healthcare system in a state of collapse.

However, both vaccines showed rates of safety and efficacy that generated endorsement by the Strategic Advisory Group of Experts on Immunization (SAGE) of the World Health Organization. In the case of the vaccine from private company Sinovac, it was 50.4% in trials in Brazil (where it is known as CoronaVac), just above the minimum requested by the WHO (in Indonesia it gave 65%, and in Turkey 91.25%, according to an article in the British medical journal).

In the case of state-owned Sinopharm, according to provisional data announced by the company, it was 79% for the prevention of symptomatic infections. (This was 86% in the study in the United Arab Emirates; Sinopharm has another vaccine, from its Wuhan branch, 72.5% effective).

But effectiveness – in clinical studies – is not the same as effectiveness – in real life, in larger, less controlled populations. “In the general population, with the two doses, at 14 days, the result was similar to the tests, just over 50%”, explains Daniela Hozbor, group director at the Vacsal laboratory at the University of La Plata and principal investigator. de Conicet, referring to the aforementioned study by the University of Chile.

“This efficiency has dropped, measured in less than 14 days, to 27%. And compared to the first dose, it was 3%. But with vaccines we do not only want to avoid infections, but serious illnesses and death: we do not have these data ”, he admitted, while adding that today there is already a decrease in severe cases among those over 60 in Chile. Statistically, saying 3% and saying 0 is almost the same thing, as study authors Juan Díaz, Eduardo Engel and Alejandro Jofré point out.

“So everything has to be looked at in detail and the vaccination has to be accompanied by preventive measures, to achieve community immunity,” Hozbor added. Sinovac or Coronavac, as it is called in Brazil, where it is produced by the Butantan Institute, has been acquired overwhelmingly by Chile – where 93% of the immune – given the low supply that the North American company Pfizer has ensured. of his vaccine called Comirnaty; something similar to what happened in Uruguay; Sinovac’s vaccine is also approved in Mexico, Colombia and Ecuador, according to journal’s vaccine “tracker” The New York Times.

The two Chinese vaccines are being studied to be two doses, with a minimum interval of 21 to 28 days, and beyond Chile’s study of the infamous 3% with one dose, there is some consensus – although disputed. – that one dose is better than nothing. ; and that both vaccines result in zero mortality from coronavirus. “For the first dose, there are data from phases one and two, and on neutralizing antibodies. With the second dose, the antibodies go up and up in more people, ”Hozbor said.

Regarding the decision to postpone the second dose, Hozbor mentioned that he is constantly evaluating how the immune response occurs also for the other two vaccines given to Argentines: the one produced by AstraZeneca and by Gamaleya (Sputnik V). “As disease databases can be crossed with immunization, this is something departments are working on to see if changes need to be made; in the meantime, the idea is to seek to have more people with at least one dose. Everything is analyzed, all the time, ”he concluded.

Covid vaccines are divided based on the strategy or platform they are made with and how they generate the immune response in the body. In addition to the “new” messenger RNA platforms (Pfizer, Moderna, CureVac), the viral vector (AstraZeneca, Sputnik V, Johnson and Johnson) and recombinant proteins (Novavax, Soberana 02), there are classic strategies such as those of the inactivated virus, faced by Chinese laboratories and Indian Bharat.

Gao Fu, director of the Center for Disease Control of China, pointed out in a later expanded technical communication that the efficacy of vaccines generated in this country could be improved (those mentioned are not the only ones) and another of his collaborators added that the country is already testing new messenger RNA platforms, which promise a planetary revolution in immunization. “Protection rates for all vaccines are sometimes high, sometimes low. Improving its effectiveness is a question that must be considered by all scientists around the world. That is why I suggest considering adjusting the vaccination process, as well as the number of doses and intervals, as well as adopting sequential vaccination with different types of vaccines, ”Gao said, according to the press. local.

Sinopharm vaccine generated clinical study in Argentina, coordinated by the Fundación Huiuda and sponsored by Elea-Phoenix laboratories. The study is closed, but the results are not yet known. Finally, concerning the variants and according to a work published in the specialized journal New England Journal of MedicineThey could even be effective against the UK.