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SINOVAC COVID-19 (CORONAVAC) VACCINE REVIEW

Updated: Jun 11, 2021

Finally, the Sinovac COVID-19 study is released and the World Health Organisation has approved it for use.

Read more about Sinovac clinical trials: https://www.who.int/news-room/events/detail/2021/04/29/default-calendar/extraordinary-meeting-of-the-strategic-advisory-group-of-experts-on-immunization-(sage)-29-april-2021

How was the Sinovac Phase I and Phase II conducted?

I will simplify the Sinovac Phase I and Phase II study in the shortest way possible because I think that we should put more emphasis on Phase III trials.



Phase I and Phase II trials (or called the COVIV-01) is a double-blind placebo-controlled study. This study is conducted in subjects from age to 18 years old to 80 years old. The subjects were given a few variants of dosages:

  1. 2 doses on Day 0, 14

  2. 2 doses on Day 0, 21

  3. 2 doses on Day 0, 28

  4. 3 doses on Day 0, 21, 42.

  5. 3 doses on Day 0, 28, 56.

The level of neutralizing antibody after two or three doses of immunization is significantly superior to that after one dose of immunization. In the two-dose immunization schedule, the neutralizing antibody level at Day 0,21 and Day 0, 28 schedules are significantly better than that at Day 0, 14. Subjects' antibodies were monitored until 90 days after the last dose and it has been concluded that there is no significant neutralizing antibody reduction observed until Day 90 after the last dose in all age groups.




Is the Sinovac vaccine safe during the Phase I and Phase II trials?

Predominantly the vaccine has not caused and lethality or death. There is certainly a common reaction ranging from local, systemic and severe adverse reaction to which anyone can be affected with any other vaccines.



Overall, the vaccine adverse reactions studied in Phase I and Phase II trials have been shown to be minimal, and severe adverse reactions are unrelated to the vaccine.



How many centers are conducting Phase III trials is for Sinovac?

The Phase III trial is a multicenter study in a few countries and the trial as are follows:

  1. COVIV-02 (Sponsored by the China National Biotec Group Company in Bahrain, Egypt, Jordan & UAE)

  2. COVIV-03 (Sponsored by Universidad Peruana Cayetano Heredia, Peru)

  3. COVIV-04 (Laboratorio Elea Phoenix S.A, Argentina)

  4. COVIV-05 (Beijing Institute of Biological Products Co., Ltd, China)

To date, only the COVIV-02, COVIV-03, and COVIV-05 have interim results available.

*BIBP (VACCINE GROUP 1) is another vaccine developed by China is the main focus of the study.

*WIBP (VACCINE GROUP 2) is another vaccine developed by China and not evaluated here. This WIBP is an investigational vaccine based on another type of SARS-CoV-2strain.

What are the effective rates of the Sinovac vaccine?

The CoronaVac (Sinovac) vaccine was 100% effective in preventing COVID-19 sufferers from being hospitalized or dying. 83.7% effective in avoiding cases that required any medical treatment, but only 50.65-75% effective at keeping people from getting infected.


Some people will prefer to get the Pfizer or the AstraZeneca Vaccine due to the higher effective rates as compared to the CoronaVac. There may be some elements that you will need to consider before making your judgment over the efficacy of the different vaccines.


I want to put it into context for you to understand the main point! Some of these vaccine-producing companies did their study in developed countries with good sanitary conditions, medical services, social welfare, and lower population density per square (density of people and a living area). These conditions reduce the risk of infection in the population therefore it produces a higher effective rate as compared to CoronaVac.

You will notice that CoronaVac's effective rates are inconsistent from country to country:

Brazil 50.4%

Chile 67%

Uruguay 61%

Turkey 91.25%

Indonesia 94%

CoronaVac did their studies in the third world, developing, and developed countries. Some of the countries had poor sanitary conditions, medical services, social welfare, and higher population density per square (density of people and a living area). These conditions increase the risk of infection in the population therefore the CoronaVac's effective rate to reduce infection is lower than other COVID vaccines. This does not mean that the CoronaVac is not effective. It appears less effective due to the conditions it was subjected to.


At the end of the day, all these vaccines have one thing in common which is 100% rates of hospitalization. Hospitalization means that the disease is severe and all brands of the vaccines have prevented 100% hospitalization.

Is the Sinovac vaccine effective in the Phase III trial?

Interim data means data that is collected during the period of intervention. So the interim data on 31/12/2020 shows the recruitment of 41301 subjects in the study.


The study was registered at clinicaltrials.gov (NCT04510207).


In COVIV-02, serum samples were collected from all participants 14 days after the second dose. A subset of participants was enrolled into an immunogenicity subgroup (~900 per site) to assess the antibody response on days 14, 28, 90, 180, and 360 after the second dose. Seroconversion 14 days after the second dose was defined as a 4-fold increase in neutralizing antibody titer compared with baseline and 99.3% of COVID-19 vaccine group seroconverted with good antibody titer as compared to 2.3% in the placebo group. The COVID-19 vaccine group in 18-59 years old participants had higher neutralizing antibodies as compares to participants above the age of 60 years old.


Interpretation:

The COVIV-02 study shows that completion of 2 injections of the COVID-19 vaccine is able to produce good rates of seroconversion and neutralizing antibody against COVID019 virus. All age groups from 19 years old and above had good seroconversion but subjects from 19-59 years old have better levels of neutralizing antibody if compared against those above the age of 60 years olds. Regardless of the level of neutralizing antibody levels; all age groups in the study had adequate antibodies against the COVID-19 virus after they have completed their vaccinations.


ADDITIONAL CLINICAL INFORMATION (for Doctors):

In the table above. 41301 subjects (as of 31/12/2021) were recruited into the phase III trial and 40408 subjects were 18-59 years old and 893 subjects were >60 years old. Of the total 41301 subjects, 85% of the participants were male and 15% were female.

*41301 subject recruited as of 31/12/2021

*BIBP (~15000 subjects) is another vaccine developed by China is the main focus of the study. *WIBP (~15000 subjects) is another vaccine developed by China and not evaluated here. This WIBP is an investigational vaccine based on another type of SARS-CoV-2strain.


After a follow-up of about 150 days from the time of vaccination; 142 subjects became infected with the COVID-19 virus (26 subjects in the WIBP group, 21 subjects in the BIBP group, 95 subjects in the placebo group respectively).


In the BIBP group (HB02 in red dotted line) -----, the actual number of participants was 14587 subjects versus 14574 subjects in the Placebo group (straight line). The graph shows a higher incidence of infective rate in the placebo group as compared to the BIBP group.


Interpretation:

The BIBP vaccinated group shows better good efficacy in preventing infection among the population studied.