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Sinovac performs poorly in clinical and real world trials, says Economist

The Manila Times logo The Manila Times 4/26/2021 Yen Makabenta

First word

THIS will infuriate the government and many compatriots who have already had themselves vaccinated with the CoronaVac (Sinovac) vaccine, or are just now planning to get inoculated with it.

Whatever the repercussions, however, I am professionally obligated to report to readers my discovery that the Economist, arguably the most authoritative and influential magazine or weekly newspaper in the world, published on April 15 a report on the efficacy of Covid-19 vaccines that will either spoil or make your day.

The magazine entitled its report, “In clinical and real world trials, China’s Sinovac underperforms.” In substance, it reported the following:

“The latest results for China’s CoronaVac vaccine, developed by Sinovac Biotech, a Beijing-based pharmaceutical company, were disappointing for the aspiring scientific and technological powerhouse. Phase 3 trials, which were conducted on health-care workers in Brazil, yielded an efficacy rate of just 50.7 percent (with a 95-percent confidence interval of 35.7 percent to 62.2 percent), just barely above the 50-percent threshold set by the World Health Organization for Covid-19 vaccines (see chart). The results of a real-world trial released a week earlier were even worse: the vaccine was estimated to be just 49.6-percent effective (11.3 percent to 71.4 percent) against symptomatic Covid-19 cases; when asymptomatic infections were included, this figure dropped to a dismal 35.1 percent.

The Chinese authorities’ reaction did little to boost confidence. After news broke of the discouraging results, Gao Fu, head of the Chinese Center for Disease Control and Prevention, admitted at a conference on April 10 that current vaccines “don’t have very high rates of protection,” and suggested that vaccines could be mixed to improve efficacy. Mr. Gao later backtracked from the comments, claiming that it was “a complete misunderstanding.”

The Economist published a chart to illustrate its report. The chart details how various Covid vaccines have fared in the critical phase three clinical trials to determine their efficacy and safety.

Predictably, the Pfizer and Moderna vaccines from the United States loomed at the top of the ratings.

Interestingly, the Sputnik V vaccine from Russia is revealed as a top performer, rating as well or better than some Western vaccines.

Disappointingly, however, the Sinovac vaccine lies at the bottom of the ratings, barely meeting the threshold of 50-percent efficacy set by the World Health Organization.

© Provided by The Manila Times The Economist continued:

“Sinovac can take some comfort from the fact that predicting the effectiveness of vaccines is devilishly hard. In an ideal world, vaccines would be tested and compared in a head-to-head trial, in which several vaccines are administered in the same setting using the same trial procedures. In the real world, however, vaccines are rigorously tested as quickly as possible, which means that trial results are not strictly comparable. Trials of the same vaccine conducted in different places, under different conditions, often have different results. In the case of Covid-19 vaccines, results can differ depending on the strains of the virus that are most prevalent, the populations tested and sometimes even the way the results are measured (e.g., whether all infections are counted, or only symptomatic ones).

That the Sinovac trials were conducted in Brazil, which harbors a variant of the virus thought to be particularly nasty, suggests some caution in assessing the outcome is in order. Indeed, preliminary results from the firm’s phase 3 trials in Turkey suggest an efficacy rate of 83.5 percent. Similar phase 3 trials are under way in Chile, Indonesia and the Philippines.

Effective or not, Sinovac has already exported approximately 120 million doses to 19 different countries, according to Airfinity, a London-based science analytics company. So far, the largest shipments have gone to Brazil, Indonesia and Turkey. In China, nearly 180 million people have already been vaccinated.

Despite the apparently poor results in stopping infections, the Sinovac vaccine, like its competitors, appears to offer remarkably good protection against severe disease and death. In the Brazil phase 3 trials, nearly 4 percent of the unvaccinated participants who were infected got severely ill; among the vaccinated, none did.

Duque gets vaccinated

Philippine authorities have launched a major effort to boost public confidence in Sinovac, because it is at this point the only vaccine that is being used by the government in its nationwide vaccination program. Public doubt whether Sinovac is good enough is strong. Only media self-censorship has muted this.

The Department of Health (DoH) and the Philippine Food and Drug Administration (FDA) have both assured the public that Covid-19 vaccines are safe and effective in preventing hospitalization and deaths from the disease, and that the benefits of vaccination far outweigh its risks.

During a regular Adverse Events Following Immunization (AEFI) briefing, the DoH and FDA reported that all the reported serious AEFIs were later found to be coincidental and totally unrelated to the vaccine after careful and thorough causality assessment conducted by the National AEFI Council (Naefic).

The DoH and FDA guaranteed that all reported adverse events were properly attended to, and reiterated that comprehensive screening prior to vaccination and sufficient monitoring after, are all in place to ensure total minimization of the risk of side effects.

To further assure vaccine safety and reiterate the importance of vaccines in the fight against the pandemic, Health Secretary Francisco Duque 3rd received his first jab of the Sinovac vaccine.

Without specifying Sinovac, Duque declared generally that vaccines are safe and effective, and stressed that the DoH is relentless in convincing more people to get vaccinated.

“As I receive my dose of the Covid-19 vaccine today, I invite everyone to do the same, and choose to be protected. Let us all take part in protecting public health and let us be in unison in spreading one message: that vaccines are safe and vaccines are effective,” Duque said.

He would be more credible if he could produce a fully certified phase 3 clinical trial result on Sinovac, showing a creditable efficacy rate.

Why phase 3 clinical trial is important

Paul Griffin of the University of Queensland in Australia published an article last year that explained the high importance of clinical trials for determining the safety and effectiveness of vaccines. He wrote:

“Clinical trials are conducted in phases, each with slightly different objectives and increasing numbers of volunteers. This is primarily to ensure subject safety but also to make sure the process is as cost-effective as possible.

Phase 3 trials are the pivotal final trials before a vaccine is approved for widespread use. While safety remains a focus, these trials are primarily about showing that people that have received the vaccine have significantly lower rates of actual infection than those that have not. To show this typically requires large numbers of volunteers, in the order of tens of thousands, depending, however, on many factors including how widespread the infection is that the vaccine is designed to protect from. While vaccines can fail to show sufficient effect and therefore fail to progress through any phase, it is the failure to provide sufficient protection in phase 3 studies where a number of potential vaccine candidates prove unsuccessful.”

The hard reality during the pandemic is that Sinovac still has to prove itself in a phase 3 clinical trial. The vaccination of Filipinos today with Sinovac is not a substitute for a phase 3 clinical trial. Neither is the much-publicized University of Chile study on Chile vaccinations. Secretary Duque by his lonesome is not a phase 3 clinical trial.

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