The vaccine in Brazilian packaging, which Brazil's institute has been working with Sinovac. Credit: Institute of Butantan

Covid-19 vaccine clinical trials recommended among Thais before actual distribution takes place

The country’s top virologist has suggested clinical trials of Covid-19 vaccines be conducted here so that medical practitioners can gain some data that fits the local setting amid concerns of reportedly low efficacy of Sinovac’s vaccine tested in Brazil’s recent clinical trial

Professor Dr. Yong Poovorawan, head of the Centre of Excellence in Clinical Virology at Chulalongkorn University’s Faculty of Medicine, said this period is the best time to conduct clinical trials on Covid-19 vaccines the country wishes to use to see real medical effects its citizens.

This is because the efficacy of vaccines varies depending on their subjects, which are different in nationalities, genders, ages, and so on.

While Thailand has planned to purchase Covid-19 vaccines in a hope to immune its citizens against Covid-19, it has had no direct data about its effectiveness at hands.

So, the professor views that while pending for the vaccines to be delivered as ordered, starting from next month on, the country could use this opportunity to conduct some trials to see medical effects that may occur to its citizens.

“I think this is the best time to test the vaccines so that we can have some medical data on our citizens. It’s still better than importing them and using them immediately without any data at hands at all,” said Prof. Yong during his live interview on NBT this afternoon.

The professor’s recommendation comes as public concerns are heightened following the report of relatively low efficacy of Covid-19 vaccine developed by China’s Sinovac Biotech during a clinical trial conducted in Brazil.

Reuters reported on Tuesday and Wednesday that researchers in Brazil released the clinical data on the company’s vaccine, which showed that its efficacy was much lower than initially announced.

It was found that the vaccine, CoronaVac, was just 50.4% effective at preventing symptomatic infections during the trial. 

The news agency cited the researcher’s data disclosure last week, which showed the 78% efficacy of the same vaccine against “mild-to-severe” cases.

The news prompted Malaysia and Singapore, which have purchase agreements with Sinovac, to say on Wednesday that they would seek more data from the company on efficacy rates before they approve and purchase the supplies, the news agency reported.

It also prompted the company to step out to defend the safety and efficacy of its experimental COVID-19 vaccine. Its Chairman Yin Weidong said at the press conference; “These Phase III clinical trial results are sufficient to prove that CoronaVac vaccine’s safety and effectiveness are good around the world,” Reuters reported.

The coming doses

Thailand has stricken a deal with Sinovac too, planning to import up to two million doses from it, with the delivery of the first 200,000 doses set in late next month.

Dr. Supakit Sirilak, Director General of the Medical Sciences Department, which also co-supervises Covid-19 distribution here, said such the news would not derail the country’s plan in seeking Covid-19 vaccines for Thai people, and the Public Health Ministry has contacted the company for more information to accompany its consideration on the registration of the vaccine here already.

So far, Sinovac is among the two companies, which have proposed for registration of their vaccines for use here, a critical condition before the vaccines can be distributed to people.

The other company is AstraZeneca, which the Thai government has also stricken a deal for a big batch of 26 million doses of the company’s vaccine plus technology transfer.

Dr. Supakit said the data from Brazil’s Butantan Institute represents the trial results among high-risk groups, which involve medical practitioners and volunteers. That’s the reason why the efficacy of the vaccine is lower than that tested for its effectiveness in disease control and in clinical severity reduction, which is 78 and 100% respectively.

The results of the clinical trials of Covid-19 vaccines at the moment are almost initial, he said, citing a clinical trial usually takes around one and a half year to obtain a thorough result.

Dr. Supakit said Sinovac’s vaccine is being developed using inactivated viruses, which is a conventional method people are familiar with. China has administered the vaccines to hundreds of thousand medical practitioners and military officers already and so far, there have been no reports of severe side effects, he said.

“The World Health Organisation’s guideline states that vaccines with over 50% effectiveness can be used, so people should not be worried about the news too much. We will try to get the vaccines which, are safe and effective, and without harmful side effects,” said Dr. Supakit, trying to allay public fears. 

Professor Yong said the effectiveness of vaccines varies depending on purposes set. They can be used to prevent infections, for disease control, or for reducing clinical severity, and satisfied percentages of effectiveness could be different.

The effectiveness of vaccines also varies among different risk groups. The higher risk the groups are, the less effective the vaccines are, he said, citing the previous results of clinical trials on HIV/AID vaccines between Thailand and some countries in Africa, which showed far different percentages of the effectiveness of the vaccines. He cautioned that only figures showing percentages cannot say about the effectiveness of vaccines, but they must be accompanied with contexts around.

Dr. Surachoke Tangwiwat, Deputy Secretary-General of the Food and Drug Administration (FDA) said Covid-19 vaccines that would be distributed here must pass the FDA’s assessment and approval, especially their safety, quality, and efficacy. 

The vaccines from both companies, he said, are still under the organisation’s assessment. The government earlier said the first registration of Covid-19 vaccines would be approved by this week.