Preliminary studies: Brazil’s Butanvac vaccine is safe and generates immune response

RIO DE JANEIRO, BRAZIL – Phase 1 clinical trials conducted in Thailand have shown that the Butanvac, a new Covid-19 vaccine candidate developed by the São Paulo state-owned Butantan Institute, is safe and has a powerful immunogenicity. The results were described in an article published last September 22 in the MedRxiv preprints website.

The trial had the participation of researchers from Mahidol University in Bangkok (Thailand), Icahn Mount Sinai School of Medicine New York (USA), and the University of Texas in Austin (USA). Internationally named NDV-HXP-S, the Butanvac is also being tested in Vietnam, in addition to Thailand and Brazil.

In all, 82 men and 128 women aged 18 to 59 took 2 doses at 28-day intervals. There were adverse effects in fewer than 1/3 of participants. The most frequent symptoms were pain and tenderness (more common in those who received the higher dosage), fatigue, headache, and myalgia.

For sanitarian physician and ex-president of the Brazilian Health Regulatory Agency (ANVISA) Gonzalo Vecina, not only is the number of phase 1 trial subjects adequate, but the Butanvac’s success in phase 1 was expected. This is because “pre-clinical trials indicate how phase 1 and 2 trials will go,” which ultimately averts any major surprises, he explains.

“The problem could occur in phase 3,” Vecina says, pointing to the stage that will indicate the Covid-19 vaccine’s effectiveness. Traditionally, phase 1 of a clinical trial only attests to a vaccine’s safety and dose selection, i.e., which dose elicits the best response in the body.

Based on the trial results, the 3 µg and 3 µg plus adjuvant formulations were selected to be assessed in the next clinical trial step, phase 2.

“We have shown that the candidate inactivated NDV-HXP-S vaccine has an acceptable safety profile and is highly immunogenic. This vaccine can be produced at low cost in any facility designed for the production of inactivated influenza virus vaccines,” the authors say in the article.

CLINICAL TRIALS IN BRAZIL

In Brazil, the Butanvac clinical trials are also currently underway. Stage A of phase 1 is being conducted in Ribeirão Preto, Guaxupé, São Sebastião do Paraíso and Itamogi. Subjects must be over 18 years of age, never have had Covid-19, not be vaccinated against SARS-CoV-2, not allergic to eggs and chicken, and not be pregnant or lactating.

In stage B, individuals who have been vaccinated or have already been infected by SARS-CoV-2 may also participate, the Butantan Institute advised.