The Sinovac-CoronaVac COVID-19 vaccine: What you need to know

Updated on 10 June 2022 pursuant to revised interim recommendations.

The WHO Strategic Advisory Group of Experts on Immunization (SAGE) has issued updated interim policy recommendations for the use of the Sinovac-CoronaVac vaccine against COVID-19. This article provides a summary of those interim recommendations; you may access the full guidance document here.

Here is what you need to know.

Who can be vaccinated?

The vaccine is safe and effective for all individuals aged 18 and above. In line with the WHO Prioritization Roadmap and the WHO Values Framework, older adults, health workers and immunocompromised persons should be prioritised.

The Sinovac vaccine can be offered to people who have had COVID-19 in the past. But individuals may choose to delay vaccination for 3 months following the infection.

Should pregnant and breastfeeding women be vaccinated?

The available data on the Sinovac-CoronaVac (COVID-19) vaccine in pregnant women are insufficient to assess either vaccine efficacy or possible vaccine-associated risks in pregnancy. However, this vaccine is an inactivated vaccine with an adjuvant that is commonly used in many other vaccines with a well-documented safety profile, such as Hepatitis B and Tetanus vaccines, including in pregnant women. The effectiveness of the Sinovac-CoronaVac (COVID-19) vaccine in pregnant women is therefore expected to be comparable to that observed in non-pregnant women of similar age. Further studies are expected to evaluate safety and immunogenicity in pregnant women.

In the interim, WHO recommends the use of the Sinovac-CoronaVac (COVID-19) vaccine in pregnant women when the benefits of vaccination to the pregnant woman outweigh the potential risks. To help pregnant women make this assessment, they should be provided with information about the risks of COVID-19 in pregnancy; the likely benefits of vaccination in the local epidemiological context; and the current limitations of safety data in pregnant women. WHO does not recommend pregnancy testing prior to vaccination. WHO does not recommend delaying pregnancy or considering terminating pregnancy because of vaccination.

Vaccine effectiveness is expected to be similar in lactating women as in other adults. WHO recommends the use of the COVID-19 vaccine Sinovac-CoronaVac in lactating women as in other adults. WHO does not recommend discontinuing breastfeeding after vaccination.

Who is the vaccine not recommended for?

The vaccine is not recommended for persons younger than 18 years of age, pending the results of further studied in that age group.

Individuals with a history of anaphylaxis to any component of the vaccine should not take it.

Persons with acute PCR-confirmed COVID-19 should not be vaccinated until after they have recovered from acute illness and the criteria for ending isolation have been met.

Anyone with a body temperature over 38.5°C should postpone vaccination until they no longer have a fever.

Is it safe?

SAGE has thoroughly assessed the data on quality, safety and efficacy of the vaccine and has recommended its use for people aged 18 and above.

Safety data is currently limited for persons above 60 years of age (due to the small number of participants in clinical trials).

While no differences in safety profile of the vaccine in older adults compared to younger age groups can be anticipated, countries considering using this vaccine in persons older than 60 years should maintain active safety monitoring.

As part of the EUL process, Sinovac has committed to continuing submit data on safety, efficacy and quality in ongoing vaccine trials and rollout in populations, including in older adults.

How efficacious is the vaccine?

A large phase 3 trial in Brazil showed that two doses, administered at an interval of 14 days, had an efficacy of 51% against symptomatic SARS-CoV-2 infection, 100% against severe COVID-19, and 100% against hospitalization starting 14 days after receiving the second dose.

What is the recommended dosage?

SAGE recommends the use of Sinovac-CoronaVac vaccine as 2 doses (0.5 ml) given intramuscularly.

SAGE recommends that a third, additional dose of the Sinovac vaccine be offered to persons aged 60 and above as part of an extension of the primary series. Current data does not indicate the need for an additional dose in persons under 60 years of age.

SAGE recommends that severe and moderately immunocompromised persons should be offered an additional dose of vaccine. This is due to the fact that this group is less likely to respond adequately to vaccination following a standard primary vaccination series and are at higher risk of severe COVID-19 disease.

WHO recommends an interval of 2–4 weeks between the first and second dose of the primary series. If the second dose is administered less than 2 weeks after the first, the dose does not need to be repeated. If administration of the second dose is delayed beyond 4 weeks, it should be given at the earliest possible opportunity. When administering an additional dose to over 60s, SAGE recommends countries should initially aim at maximizing 2-dose coverage in that population, and thereafter administer the third dose, starting with the oldest age groups.

Is a booster dose recommended for this vaccine? 

A booster dose may be considered 4 – 6 months after completion of the primary vaccination series, starting with the higher priority-use groups, in accordance with the WHO Prioritization Roadmap.

The benefits of booster vaccination are recognized following increasing evidence of waning vaccine effectiveness against mild and asymptomatic SARS-CoV-2 infection over time. 

Either heterologous (a different vaccine product to Sinovac) or homologous (a booster dose of Sinovac) doses can be used. Studies in Chile and Brazil found that heterologous boosting resulted in superiormore robust immune responses than homologous boosting.

Can this vaccine be ‘mixed and matched’ with other vaccines?

SAGE accepts two heterologous doses of WHO EUL COVID-19 vaccines as a complete primary series.

To ensure equivalent or favourable immunogenicity or vaccine effectiveness either of the WHO EUL COVID-19 mRNA vaccines (Pfizer or Moderna) or the WHO EUL COVID-19 vectored vaccines (AstraZeneca Vaxzevria/COVISHIELD or Janssen) can be used as a second dose following a first dose with the Sinovac vaccine dependant on product availability. 

Does it prevent infection and transmission?

There is currently no substantive data available related to the impact of COVID-19 vaccine Sinovac-CoronaVac on transmission of SARS-CoV-2, the virus that causes COVID-19 disease.

In the meantime, WHO reminds of the need to stay the course and continue practicing public health and social measures that should be used as a comprehensive approach to prevent infection and transmission. These measures include wearing a mask, physical distancing, handwashing, respiratory and cough hygiene, avoiding crowds and ensuring adequate ventilation according to local national advice.

Does it work against new variants of SARS-CoV-2 virus?

In an observational study, the estimated effectiveness of Sinovac-CoronaVac in health workers in Manaus, Brazil, where P.1 accounted for 75% of SARS-CoV-2 samples was 49.6% against symptomatic infection (4). Effectiveness has also been shown in an observational study in Sao Paulo in the presence of P1 circulation (83% of samples). 

There are still insufficient data for Omicron.

SAGE currently recommends using this vaccine, according to the WHO Prioritization Roadmap.

How does this vaccine compare to other vaccines already in use?

We cannot compare the vaccines head-to-head due to the different approaches taken in designing the respective studies, but overall, all of the vaccines that have achieved WHO Emergency Use Listing are highly effective in preventing severe disease and hospitalization due to COVID-19.