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Will a COVID-19 vaccine that's 50% effective be good enough?

By JUSTINE PUNZALAN Published Jan 15, 2021 7:14 am Updated Feb 28, 2021 11:38 pm

Lawmakers and certain quarters continue to question the government’s plan to procure 25 million doses of COVID-19 vaccine from Chinese pharmaceutical company Sinovac Biotech.

The Philippine government began the rollout of Sinovac vaccine on March 1 with Cabinet members and hospital directors getting the first jabs in ceremonies held at UP-PGH, Lung Center, Veterans Memorial Medical Center and Tala Hospital. The 600,000 doses of Sinovac were donated by the Chinese government and arrived in Manila on Feb. 28. 

The Sinovac vaccine tagged CoronaVac is reportedly the second most expensive vaccine in the world, next to Moderna, with an estimated price of P3,629.50 for two doses. That, on top of its efficacy rate of 50.4% in a clinical trial in Brazil—a far cry from Pfizer’s reported 90%—continues to fuel suspicion and distrust toward CoronaVac.

But Dr. Edsel Salvaña, a member of the Inter-Agency Task Force (IATF) Technical Advisory Group, said it’s good enough to keep you from getting confined in a hospital’s Intensive Care Unit (ICU).

He explained this during the Presidential Communications Operations Office (PCOO) virtual presser on Thursday, Jan. 14.

“Importante po nating intindihin, emergency use tayo ngayon, so ‘yung vaccines na for clinical trials, mabilisan po ang pagkilos nila. Hindi po minadali—mabilisan—dahil gumagawa sila ng paraan na gamitin natin ang mga alam natin for the last 17 years—they have been already developing vaccins for SARS una, ‘tapos sa MERS. Tapos nire-purpose lang nila ‘yung vaccine na gagamitin para sa SARS-CoV-2 or sa COVID-19,” said Salvana.

“Para doon sa emergency use po kasi, ang sinet na minimum efficacy ng WHO (World Health Organization) na sa tingin nila will be a useful vaccine is 50% talaga,” he continued. “So any vaccine that prevents 50% of disease—whether it’s mild, moderate, or severe—is potentially a useful vaccine.”

Vaccines, according to the Centers for Disease Control and Prevention (CDC), are only meant to “almost never cause illness.” Yet, it is sure to “cause the immune system to produce T-lymphocytes and antibodies” to fight the disease in the future.

Like most vaccines, COVID-19 booster shots (whatever the efficacy rate) will not keep you 100% COVID-free. However, it can stop the disease from developing into a severe case in case you are infected with it, said Salvaña. He elaborated on this by using the flu vaccine as an example.

“Ikumpera natin sa influenza vaccine. Ang ating flu vaccine ay 30 to 70% effective for preventing clinical disease. Pero 82% siya effective at preventing you from ending up in the ICU from influenza,” he said.

“So hindi lang ibig sabihin na 50%, 30%, o 70% na nakaka-prevent ng disease dahil isipin niyo, you will prevent 82% of the disease—of people na nagkaroon ng trangkaso—para malagay sa Intensive Care Unit.”

Ang bakuna, hindi lang doon sa general efficacy rate nila, kung hindi ‘yung propensity to prevent severe disease.

Salvaña said the same goes for the Sinovac vaccine: “So ganun ang nangyayari dito, ‘yung minimum na 50% is for general disease. And nung tininingan nila yung datos nila, lalong lalo na doon sa Brazil, nakita nila na ‘yung taong nagkaroon… mild mostly ‘yung kanilang disease. At noong kinumpara nila sa mga hindi nabakunahan, wala po talagang naospital na with severe disease doon.”

“So iyon ‘yung importante na tingnan natin. Ang bakuna, hindi lang doon sa general efficacy rate nila, kung hindi ‘yung propensity to prevent severe disease,” he added.

“Puwede pa rin siyang mahawa pero kung mahawa ka na may bakuna ka na, chances are, hindi ka talaga magkakaroon ng severe COVID and that would be very useful.”

Efficacy rate “not a criteria” in vaccine distribution

Health Undersecretary Dr. Maria Rosario Singh-Vergeire, meanwhile, said the efficacy rate of vaccines is not the only factor considered in vaccine distribution in the country.

“Hindi tayo mag-depend sa efficacy rate kung ano ang ilagay natin sa bawat lugar o bawat sektor. Ang lagi nga naming sinasabi, kapag nakapasok na ang bakuna [sa bansa], ibig sabihin, nakapasa na sa ating Food and Drug Administration (FDA). Lahat ay ico-consider na naming ligtas at makakapagsugpo sa ating pandemya,” Vergeire said in a virtual press briefing on Friday, Jan. 15.

Aside from the standard efficacy rate set by the World Health Organization, FDA would only approve the distribution of a COVID-19 vaccine in the Philippines after it has passed a matrix of tests and requirements stated on the FDA’s Development and Licensure of Vaccines to Prevent COVID-19 industry guide.

It includes verification of “chemistry and manufacturing controls” studies to address vaccine-associated respiratory diseases, as well as presentation of trial design, statistical, and safety measures.

“So, we will not rely or use efficacy rate para sabihin natin, o makagawa tayo ng criteria, kung ano ang bakuna ang ilalagak natin sa bawat lugar o ‘di kaya sa bawat sector,” said Vergeire.

The DOH undersecretary added that logistics will play a “critical” role in the nationwide vaccination program.

“Diyan magkakaroon ng differences across the regions, ang population, natin,” she said. “So kung ang requirement natin ay highly technical logistical requirement, like for example, those [vaccines] requiring the ultra low storage freezers, ito po talaga ay hindi natin malalagay sa far-flung areas.”

“Kaya kasama na po sa stratehiya ng ating gobyerno ay ‘yung magkaroon tayo, mailagak natin ang mga bakuna dito sa urban areas natin. Kasi sila ang may capability at nandiyan ang mga facility which can store these vaccines,” she continued.

“Most of the vaccines would require two to eight degrees [storage temperature], puwede po ‘yan kahit saang region,” Vergeire added.

“So ‘yun lang ang magiging difference natin. But the efficacy rate will not be used as a criterion to distribute or allocate these vaccines across our sectors, across the regional areas, in our country.”

Hindi tayo mag-depend sa efficacy rate kung ano ang ilagay natin sa bawat lugar o bawat sektor. Ang lagi nga naming sinasabi, kapag nakapasok na ang bakuna, ibig sabihin, nakapasa na sa ating Food and Drug Administration.

Philippine National Vaccine Roadmap

The acquisition and distribution of vaccines in the country entail a lot of work beyond those carried out by the FDA.

The entire Philippine National Vaccine Roadmap, launched by vaccine Czar and IATF chief implementer Secretary Carlito Galvez Jr. on Nov. 5, 2020, consists of seven key stages to be led by different government agencies.

According to Galvez, the most critical stage is the beginning phase of the roadmap, which involves the scientific evaluation and selection of the vaccines spearheaded by the DOH and the Department of Science and Technology (DOST).

In the second stage called “Access of Acquisition” or “Guarantee of Access”, the Department of Foreign Affairs (DFA) and the Department of Finance (DOF) will secure access to vaccines manufactured by various global pharmaceutical companies.

The third stage is the actual procurement process led by the Procurement Service of the Department of Budget and Management (PS-DBM) and DOF, and supervised by the TaskGroup Resource Management & Logistics (TGRML). During this phase, the agencies must ensure that “vaccine acquisition and development is both cost-effective and time-efficient,” the DOH stated.

The PS-DBM and TGRML will also implement the fifth phase of the roadmap or the deployment of vaccines to the Philippines.

Stage six focuses on the nationwide implementation of the vaccination plan, which will be a collaboration among the DOH, local government units (LGUs), and other national agencies.  

Lastly, the DOH, DOST, and the University of the Philippines-National Institute of Health (UP-NIH) will manage and oversee the assessment, evaluation, and monitoring of the vaccine rollout to the public.