The Sinovac vaccine, CoronaVac, is an inactivated vaccine developed by a private Chinese company. It requires two doses given 2-4 weeks apart, similar to mRNA vaccines and most adenovector vaccines. Currently, the Sinovac vaccine is approved in China and for emergency use in other countries.
In clinical trials worldwide, the Sinovac vaccine has been shown to be 50% to 79% effective in preventing symptomatic Covid infection. While CoronaVac may not be as effective as the mRNA vaccines in use, it is still helping to bring the pandemic under control. Healthy individuals who receive both doses appear to be protected from severe disease and death. Regardless of which vaccine you receive, any vaccine is better than no vaccine, so be sure to get yours today.
How the Sinovac Vaccine Works
There are many types of vaccines, but they all work to create an immune response to help your body fight future infections. CoronaVac is an inactivated vaccine that relies on producing the virus and then inactivating it so that it cannot cause infection but does cause immunity. This technology has been around for a long time and is the same technology that has developed the Hepatitis A, Flu, polio, and rabies vaccines.
Clement Lewin, Ph.D., MBA, Principal at CSL Vaccine Consulting, notes, “[The Sinovac Vaccine] has demonstrated that inactivated vaccines are a viable approach to developing a COVID vaccine and bodes well for other vaccines being developed on the platform.” Below is a diagram of how this type of vaccine is made.
Inactivated vs. mRNA
The main advantage of distributing an inactivated vaccine compared to an mRNA vaccine is that they do not require the same storage level to preserve. Inactivated vaccines can be stored in a regular fridge, making them more accessible for places that do not have access to state-of-the-art freezers.
For reference, the Moderna vaccine is stored at minus 20 degrees Celsius (-4 F), and the Pfizer vaccine needs to be stored at minus 70 degrees Celsius (-94 F) or below. This leads to supply chain issues worldwide where adequate freezers are unavailable.
Efficacy of CoronaVac
The exact efficacy of the Sinovac vaccine is unclear due to the design of the studies to evaluate it. Regardless, all of the studies released surpass the World Health Organization's minimum of 50% efficacy, listing CoronaVac as the 7th to be authorized. 11 countries have placed orders for the Sinovac vaccine, including Brazil, Turkey, Singapore, and Indonesia.
There is currently no evidence on the ability of the Sinovac vaccine to prevent transmission of COVID-19. While it is still recommended by the Strategic Advisory Group of Experts (SAGE) on Immunization, we cannot ignore public health practices and social measures just yet.
In Brazil, the efficacy of the Sinovac vaccine is reported to be 50.4% overall. The trials included people who were not experiencing obvious symptoms. Nonetheless, the Sinovac vaccine was 78% effective against mild Covid-19 cases and 100% effective at preventing severe cases. Brazil authorized the use of the Sinovac vaccine on January 17, 2021.
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The trials conducted in Turkey included persons with a confirmed negative PCR test at enrollment. The efficacy against Covid-19 with at least one symptom was 83.5 percent. As of July 1, Turkey offers a third dose of both the Sinovac vaccine or Pfizer vaccine for healthcare workers and those over 50 years old. Turkey is one of the first countries to begin rolling out COVID-19 booster vaccines.
Indonesia rolled out a free COVID-19 vaccination campaign targeting young working people. Indonesia gave the vaccine emergency authorization on January 11, 2021, and the government was promised 125 million doses of the Sinovac vaccine. Since the government has only carried out trials including people in the 18-59 age group, these trials have reported a 65.3% efficacy.
Where CoronaVac is in Use
The Sinovac vaccine will most likely never make it to market in the U.S. because the demand for vaccines is being met. In places where there are supply constraints, particularly in low and middle-income countries, CoronaVac can help reduce the spread of the coronavirus.
Dr. Lewin shared, “People living in China and low and middle-income countries where the Sinovac vaccine is or will be available are most likely to benefit directly from the vaccine. People living in high-income countries or in countries where CoronaVac isn’t available should benefit indirectly as immunization with the vaccine will help prevent the emergence and spread of variants and hopefully mitigate the impact of the pandemic”. Below is a map of where the Sinovac vaccine is currently in use.
Malaysia has stopped administering the Sinovac vaccine because the country has sufficient doses from other vaccines. Moving forward, Malaysia will be relying on the Pfizer mRNA for the remainder of the vaccination rollout; they had secured 16 million doses of the Sinovac vaccine but 45 million of the Pfizer vaccine, which is enough to cover 70% of the population.
The Sinovac Vaccine Against Variants
To date, there is very little data on the effectiveness of the Sinovac vaccine against variants. It is expected that CoronaVac will be less effective against more contagious variants of the SAR-CoV-2 virus, given that its initial efficacy was only around 50%. Although, in Brazil, where P.1 accounted for 75% of SARS-CoV-2 samples, the Sinovac vaccine was 49.6% against symptomatic infection.
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Sinovac Vaccine Frequently Asked Questions (FAQs)
The Sinovac vaccine is one of the less heard of vaccines currently available. It is not currently being distributed in the U.S., but it is helping to combat the pandemic worldwide. Read on to learn more about CoronaVac.
How efficacious is the Sinovac vaccine (CoronaVac)?
A large phase 3 trial in Brazil showed that the Sinovac vaccine is 100% effective against severe COVID-19 and 100% effective against hospitalization starting 14 days after receiving the second dose. Even though it is less effective than the mRNA vaccines, 51% overall, it does protect against severe sickness and death.
Is the Sinovac vaccine safe for pregnant women?
There is no reason to believe the Sinovac vaccine will cause complications for pregnant women. Other inactivated vaccines such as the Hepatitis A and polio vaccines are made with the same technology and are deemed safe and effective for pregnant women. The potential benefits of the Sinovac vaccine outweigh the risks, and further studies will include pregnant women in recruitment.
Where is the Sinovac vaccine currently in use?
At the moment, China owns enough doses to vaccinate over half of the population fully. China issued conditional approval on February 6, 2021, and expanded authorization to children and adolescents on June 4, 2021. The World Health Organization gave emergency authorization to the vaccine on June 1, 2021. Coronavac is now available for emergency use in Mexico, Brazil, Colombia, Chile, Uruguay, Botswana, South Africa, Turkey, Tunisia, Ukraine, Pakistan, Indonesia, and Malaysia.
Governments and private companies have invested in multiple platforms for vaccine development during the pandemic, like inactivated and mRNA technologies. The Sinovac vaccine has been approved for widespread use in China and several other countries for emergency use.
The most important part of overcoming the COVID-19 pandemic is getting vaccinated. The more people who get vaccinated, the less chance there is for additional variants to arise. There is no better way to protect yourself and the people you love than to get vaccinated.
This post is informed in part by Clement Lewin, Ph.D., MBA, Principal at CSL Vaccine Consulting.
Alexis Bryan MPH, is a recent graduate of Columbia’s Mailman School of Public Health. She is passionate about increasing access to care to improve health outcomes. Outside of work, she loves to travel, read, and pay too much attention to her plants.