The vaccine cuts your risk of getting sick in half.
Em meio à maior crise sanitária do século, o Brasil chegou ao início de 2021 com uma resposta concreta em mãos: a CoronaVac, desenvolvida pela Sinovac em parceria com o Instituto Butantan, demonstrou eficácia suficiente para proteger populações vulneráveis e aliviar a pressão sobre os sistemas de saúde. Com 50,38% de eficácia geral e 78% contra casos leves, a vacina não encerra a pandemia, mas representa um passo mensurável na longa travessia coletiva. São Paulo anunciou o início da vacinação para 25 de janeiro, enquanto o governo federal articulava a distribuição nacional pelo SUS — um momento em que ciência, política e esperança se encontraram, ainda que de forma imperfeita.
- A divulgação de 50,38% de eficácia gerou debate imediato: o número ficou abaixo dos 78% anunciados dias antes, revelando que a proteção varia conforme a gravidade dos casos analisados.
- A Anvisa ainda não havia aprovado o uso emergencial da vacina, e o prazo de dez dias para análise do pedido — submetido em 8 de janeiro — mantinha o calendário de vacinação suspenso por uma decisão regulatória.
- A opacidade nos contratos entre o governo de São Paulo e a Sinovac — valores parcialmente desconhecidos, termos confidenciais — alimentou desconfiança pública num momento em que transparência seria essencial.
- O governo federal anunciou a compra de todas as doses disponíveis da CoronaVac para o programa nacional, colocando em xeque o plano autônomo de São Paulo e subordinando o estado ao calendário federal.
- Com 10,8 milhões de doses recebidas e o restante previsto para março, a logística de distribuição entre estados permanecia indefinida, deixando a equidade do acesso como uma promessa ainda sem garantia.
Em 12 de janeiro de 2021, o governo de São Paulo anunciou que a CoronaVac havia atingido 50,38% de eficácia geral nos ensaios clínicos brasileiros — resultado que mede a capacidade da vacina de prevenir casos sintomáticos de COVID-19, leves ou graves. Cinco dias antes, o Instituto Butantan havia revelado um dado mais específico: 78% de eficácia contra casos leves, indicando que a maioria dos vacinados que contraíram o vírus não precisou de hospitalização.
A vacina utiliza tecnologia de vírus inativado, uma abordagem consolidada na qual o coronavírus é tratado em laboratório para perder a capacidade de replicação. Os ensaios de fase 3 no Brasil envolveram 16 centros de pesquisa em sete estados e o Distrito Federal. Dados de segurança publicados na revista The Lancet não identificaram reações adversas graves; o efeito colateral mais comum foi dor no local da injeção. O esquema vacinal prevê duas doses com intervalo de 21 dias, conforme o plano paulista.
No início de janeiro, a vacina ainda aguardava autorização de uso emergencial da Anvisa, com pedido protocolado em 8 de janeiro e prazo padrão de dez dias para análise. Das 46 milhões de doses contratadas, 10,8 milhões já haviam chegado ao Brasil — parte pronta para uso, parte como insumo para processamento no Butantan. O restante estava previsto para março. A fábrica do instituto destinada à produção completa ainda estava em construção.
O plano de vacinação de São Paulo previa iniciar em 25 de janeiro, priorizando profissionais de saúde, povos indígenas, quilombolas e idosos. A primeira fase deveria alcançar 9 milhões de pessoas. No entanto, o governo federal anunciou a compra de todas as doses disponíveis para o programa nacional, distribuídas gratuitamente pelo SUS — o que poderia subordinar o calendário estadual ao federal. Crianças, adolescentes, gestantes e imunossuprimidos não participaram dos ensaios e não seriam vacinados nessa fase inicial. Para a população geral fora dos grupos prioritários, nenhum prazo havia sido definido.
São Paulo's government announced on January 12 that CoronaVac, the COVID-19 vaccine developed by Chinese pharmaceutical company Sinovac in partnership with the Butantan Institute, had achieved 50.38% overall efficacy in Brazilian clinical trials. This figure measures the vaccine's ability to prevent symptomatic COVID-19 cases, whether mild or severe. The announcement came five days after the institute had revealed a more granular finding: 78% efficacy against mild cases specifically, meaning that among vaccinated volunteers who contracted the virus, 22 out of every 100 experienced only mild symptoms without requiring hospitalization.
CoronaVac uses inactivated virus technology, a well-established approach in which the coronavirus is exposed to heat and chemicals in the laboratory to render it incapable of replication. This means no live Sars-CoV-2 virus is present in the vaccine solution, reducing the risks associated with this type of immunization. The Butantan Institute, which is linked to São Paulo's state government, coordinated the phase 3 trials in Brazil, which involved 16 clinical research centers across seven states and the Federal District. Safety data published in The Lancet showed no serious adverse reactions; the most common side effect was pain at the injection site.
The vaccine requires two doses, with an interval of 14 to 28 days between them—São Paulo's vaccination plan specified 21 days. As of early January, the vaccine had not yet received final approval from Brazil's health regulator, Anvisa, though an emergency use authorization request was submitted on January 8 for the 6 million doses already arrived from China in ready-to-use form. Anvisa's standard review period for such requests is ten days. The full registration application had not yet been filed; Butantan's director, Dimas Covas, said Sinovac would submit it but provided no timeline.
The partnership between Butantan and Sinovac involved financial commitments that remained partially opaque. In September 2020, São Paulo Governor João Doria signed an agreement valued at US$90 million for 46 million doses. It was unclear whether this amount included or was separate from the R$85 million the state had reportedly paid for an earlier agreement in June. The contract terms themselves were kept confidential and not fully disclosed to the public. Currently, the vaccine is not manufactured in Brazil; the Butantan facility intended for full production remains under construction, with completion originally targeted for the end of 2021. Once operational, it was expected to produce 100 million doses annually. For now, Butantan processes imported raw materials—diluting, filling, and labeling them—while some doses arrive from China already prepared for injection.
São Paulo's vaccination plan called for healthcare workers, indigenous peoples, and quilombo residents to receive the first doses beginning January 25, followed by elderly residents in descending age brackets. The first phase was projected to reach 9 million people: 7.5 million aged 60 and older, and 1.5 million healthcare workers, indigenous people, and quilombo residents. However, this timeline faced uncertainty after the federal government announced it would purchase all available CoronaVac doses for inclusion in the national vaccination program. The state's contingency coordinator, João Gabbardo, indicated that if the federal government began vaccinations before January 25, São Paulo would follow the national calendar instead.
The federal government signed a contract with Butantan for 46 million doses, with an option to purchase an additional 54 million, potentially totaling 100 million. The vaccine would be distributed free through Brazil's unified health system, the SUS. By early January, São Paulo had received 10.8 million doses in total—some ready for use, others as raw materials for processing—with the remainder of the 46 million expected by March. Distribution to other states and the precise allocation per state remained undetermined. Children, adolescents under 18, pregnant women, and immunocompromised individuals had not participated in trials and would not receive the vaccine in this initial phase. For the general population outside priority groups, no vaccination timeline had been announced.
Citações Notáveis
The vaccine is safe with no serious adverse reactions; the most common side effect was pain at the injection site.— The Lancet study on CoronaVac phase 1 and 2 trials
A Conversa do Hearth Outra perspectiva sobre a história
Why does a 50% efficacy rate matter when other vaccines showed much higher numbers?
Because context matters. Fifty percent means the vaccine cuts your risk of getting sick in half. That's meaningful protection, especially when you're talking about preventing hospitalization and severe disease. The 78% figure against mild cases tells you something different—it's saying the vaccine is quite good at keeping you out of the hospital if you do get infected.
So people knew this was a Chinese vaccine. Did that change how they felt about it?
The government certainly thought it mattered. They started calling it the "Butantan vaccine" instead of the "Chinese vaccine" after the term took on a negative charge. The partnership was real—Sinovac developed it, Butantan ran the Brazilian trials—but the branding became political.
The contract was confidential. Why would they hide the terms?
That's the question nobody could answer at the time. We knew the September deal was $90 million for 46 million doses, but there was an earlier agreement in June for R$85 million that was also kept secret. Whether one included the other, or they were separate—nobody said.
They hadn't even built the factory yet?
Not yet. They were still processing doses by hand at an existing facility, diluting and filling vials. The factory that would eventually produce 100 million doses a year was still under construction, originally due to finish by the end of 2021.
Who got it first?
Healthcare workers, indigenous people, and quilombo residents starting January 25. Then elderly people in age brackets—75 and up first, then working down to 60. But that plan was fragile. The federal government bought all the doses, so everything depended on whether they'd follow São Paulo's schedule or impose their own.
Could you get it if you weren't in those groups?
Not yet. Children, teenagers, pregnant women, people with immune disorders—none of them had been tested. So no one knew if it was safe for them. Everyone else just had to wait.