MANILA, Philippines — In less than a year, scientists were able to develop candidate vaccines against COVID-19, raising hopes that the end may be near for the pandemic, even as health experts still urge caution.
This extraordinary feat, however, is being undermined by a flood of falsehoods that even social media giant Facebook took note of, as it committed to “remove false claims” about the coronavirus vaccines on its platform.
Normally, it takes the scientific community years, even decades, to develop a vaccine against an infectious disease.
Tests, trials
Take the case of measles, which has plagued mankind for centuries. It was only in 1963 that the first measles vaccine was licensed in the United States.
In contrast, the development of at least three candidate vaccines against COVID-19 only took 11 months since the World Health Organization (WHO) first learned on Dec. 31 last year of a clustering of pneumonia cases of unknown cause in Wuhan, China.
These vaccines were developed by Pfizer/BioNTech, Moderna/US National Institutes of Health (NIH) and Oxford/AstraZeneca.
WHO chief scientist Soumya Swaminathan explained that just because these vaccines came out on record time doesn’t mean that there were steps in the scientific process of developing a vaccine that were skipped.
She noted that all of these vaccines underwent the preclinical tests as well as the three-phase human clinical trials.
‘Safety data’
“Timelines were accelerated by overlapping Phase 1 and 2 by regulatory agencies willing to be flexible, looking at submissions, so even before Phase 1 is complete they are already ready, if everything goes well, to approve Phase 2,” Swaminathan said.
She pointed out “That doesn’t normally happen with vaccine or drug development.”
In the first two phases of the clinical trials, the candidate vaccine’s safety, efficacy and proper dosage are tested on up to a thousand patients.
Swaminathan said it also helped that substantial investments have been made in developing the vaccines, along with the recent advances in science and technology.
“So it’s building on scientific progress over the last few years. It’s accelerating clinical trials by overlapping and it’s also by investing in manufacturing,” she said.
Emergency use
Filipino infectious disease expert Dr. Edsel Salvana said another reason for the speed of the vaccines’ development is because quite a number of them were based on “known technology and repurposed SARS and MERS vaccines which were in advanced stages of development.”
“Despite the urgency of the matter, the US Food and Drug Administration (FDA) still required at least two months of safety data from tens of thousands of patients before even considering a vaccine for review. These patients will continue to be followed for longer term side effects even after the vaccine is approved to have some insight into longer term issues, if any emerge,” Salvana said in a Facebook post.
This week, President Duterte gave the FDA the power to grant an emergency use authorization (EUA) to candidate COVID-19 vaccines. An EUA is issued to manufacturers particularly in times of health emergencies, and when the benefits of using a candidate vaccine or drug outweigh its risks.
FDA Director General Eric Domingo noted that an EUA doesn’t exempt a manufacturer from fully completing the development of its vaccine.
Once an EUA is issued and the vaccine is rolled out in the country, Domingo said both the FDA and the Department of Health (DOH) will conduct postauthorization monitoring of side effects, if any.
He said this mechanism also ensures that when there are “unusual or suspicious adverse events,” these can immediately be investigated and they can decide on whether to continue further vaccination.
“It’s really important to have a very strong monitoring and surveillance mechanism, both passive and active,” Domingo said.
Based on the results of their clinical trials, the vaccines developed by the three leading manufacturers were found to have varying degrees of efficacy.
Pfizer/BioNTech reported their vaccine to have an efficacy rate of 95 percent, while Moderna/US NIH’s vaccine was at 94.1 percent. Oxford/Zeneca’s vaccine has an average efficacy rate of 70 percent.
According to Domingo, the effectiveness of a vaccine may differ from the published efficacy rates since their data was based on trials conducted in a well-controlled environment.
Factors that may affect a vaccine’s efficacy in the real world setting are uncertainties in the cold chain and patients not being able to strictly follow their immunization schedule, among others.
“Effectivity is the real-life application of a vaccine’s efficacy. [The efficacy rate] is the result we can expect if we use the vaccine in the right and prescribed way,” he said.
Virus case update
On Saturday, the DOH logged an additional 1,733 COVID-19 cases, raising the national tally to 438,069.
Davao City reported the most number of new infections, 162, followed by Quezon City (92), Benguet (80), Rizal (70) and Laguna (66).
Another 133 patients have recovered from COVID-19, bringing the total number of survivors to 399,582. The death toll, however, increased to 8,526 as 17 patients succumbed to the severe respiratory disease.
The recoveries and deaths left the country with 29,961 active cases, of which 86 percent are mild, 6.7 percent asymptomatic, 0.27 percent moderate, 2.4 percent severe and 4.6 percent critical.