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Sinovac Vaccine in 12 easy questions

Written by Dr David Owens New call-to-action

What type of vaccine is Sinovac?

Answer: Sinovac is an inactivated vaccine

Sinovac is a traditional inactivated vaccine. This vaccine can be stored in a standard fridge making widespread use easier than newer mRNA vaccines. It is given as 2 shots 28 days apart. The Hong Kong expert committee released a summary of the scientific committee findings. The report is available here.


Is Sinovac an effective vaccine?

Answer: Yes

The WHO approved Sinovac vaccine on the basis of a large phase 3 trial in Brazil which showed that two doses, administered at an interval of 14 days, had an efficacy of 50.7% against symptomatic SARS-CoV-2 infection, 100% against severe COVID-19, and 100% against hospitalization starting 14 days after receiving the second dose. A study published in the Lancet, of 11,000 volunteers in Turkey, showed 83.5% efficacy in preventing symptomatic disease. This study was in mostly younger patients and had a short follow up because the vaccine was approved for emergency use during the study period. We do not yet have large population studies of effectiveness.


Is Sinovac a safe vaccine?

Answer: Yes

The WHO strategic advisory group of experts on immunization (SAGE) has analysed the safety data for Sinovac and approved the vaccine. The Hong Kong expert committee on vaccination has approved Sinovac for people over 3 years old. Safety monitoring is ongoing and large numbers of inactivated vaccines have now been given worldwide, especially in China.


Does Sinovac vaccine have side effects?

Answer: Yes but the vast majority are mild and self-limiting

The following are the reported incidence for side effects with Sinovac:

  Side Effects May Affect
Very common
  • Pain at injection site
  • Headache
  • Fatigue
≥ 10% people
  • Injection site:
    itching or redness
  • Muscle aches
  • Nausea
  • Diarrhoea
  • Joint Pain
  • Cough
  • Chills
  • Itchy skin
  • Loss of appetite
  • Runny nose
  • Sore throat
  • Nasal congestion
  • Abdominal pain
1%  - 10% people
  • Burn at injection site
  • Vomit
  • Allergic reaction
  • Skin rashes
  • Fever
  • Tremor
  • Flushing
  • Dizziness
  • Drowsiness
0.1% - 1% people
  • Muscle spasms
  • Eyelid swelling
  • Nosebleeds
  • Abdominal distension
  • Constipation
  • Loss of sense of smell
  • Eye swelling
  • Hot flashes
  • Hiccups
  • Red eyes
0.01% - 0.1% people

Mild side effects are relatively common. In a recent survey of OT&P patients, only 2 out of 3,233 patients indicated that the side effects would prevent them from taking another vaccination. In our survey, mild side effects were less common with Sinovac than with the BioNTech vaccine. We have summarised the evidence of side effects of Covid vaccines in another article.


Will I need a booster dose of Sinovac vaccine?

Answer: Yes

The Hong Kong expert committee has advised booster shots for anyone who has received Sinovac. Anyone who has been given Sinovac will be offered a booster either with BioNTech or Sinovac.

We know from both antibody studies, and population studies of effectiveness, that the immune response to Sinovac is less strong than BioNTech and tends to wane more quickly. The government advises people who have previously taken Sinovac that BioNTech is more effective as a booster.


Does Sinovac prevent transmission of COVID-19?

Answer: No, there may be a small reduction in transmission

There is no evidence that Sinovac prevents the transmission of the SARS-Cov-2 virus. There is a possibility of a small reduction in transmission although the evidence for reduction is transmission is better for the mRNA vaccines. The impact of transmission is also less for the newer variants.


Is Sinovac effective against the Omicron Variant?

Answer: It is too early to say. It is likely to be effective to a reduced degree. We need more data

Reports from China suggest that Sinovac is 59% effective against the Delta variant . Early data suggests that Omicron is better at avoiding existing immunity than Delta. It seems likely that Sinovac vaccination will be less effective but we need more data.

We have a further article Omicron which we will continue to update as more evidence arises.


Can children have Sinovac?

Answer: Yes

In Hong Kong, Sinovac has recently been approved for Children over 3 years of age. In the first instance Sinovac will be offered to Children aged 12-17 years. Sinovac has been given to children and adolescents in China and other countries with no reported increase in side effects[1]. However, Sinovac contains Aluminium Hydroxide as an adjuvant and as yet there have been no large peer-reviewed trials of safety in children.

We have written another article on Covid vaccinations for children. The arguments for vaccinating children are balanced. Currently there is more peer-reviewed evidence for BioNTech than for Sinovac in children.


Can pregnant and lactating mothers have Sinovac?

Answer: No

In Hong Kong, Sinovac is not recommended to pregnant or lactating mothers. BioNTech is given internationally. In Hong Kong, the CHP advises pregnant and lactating mothers to discuss the risk-benefit of BioNTech vaccination with their doctor.


Do I need a body check before I have a COVID-19 Vaccine?

Answer: No

Would you have a body check before having a flu jab? People who have underlying medical conditions should ideally always have them controlled. Individuals with other illnesses are generally at greater risk of COVID-19 and it is even more important that they are vaccinated.


I have high blood pressure/diabetes, can I have Sinovac?

Answer: Yes

If you have high blood pressure or diabetes, it should ideally be controlled but it is even more important for you to be vaccinated.


Does Sinovac vaccine reduce the impact of Long Covid?

Answer: Probably, but we do not yet have enough evidence to be certain

Long Covid is posing a significant burden to health systems. There is increasing evidence that vaccination significantly reduces the incidence of Long Covid. We do not yet have evidence for this benefit specifically for Sinovac but it seems likely that this is a result of vaccinations in general. More evidence is needed to be certain.

Interested in BioNTech vaccine? Check out our article BioNTech vaccine in 12 easy questions.

In a further article, we compare the vaccines head-to-head and ask which is the best vaccine.



1. Scientific Committee on Emerging and Zoonotic Diseases and Scientific Committee on Vaccine Preventable Diseases. Centre for Health Protection. (2021, September 15). Retrieved September 16, 2021, from

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