The continuous decline in Covid-19 cases in the Philippines while other countries are experiencing spikes may be a result of both science and luck, an infectious disease expert said Saturday.

In a Facebook post, Department of Health-Technical Advisory Group (DOH-TAG) member Edsel Salvana said the Filipinos’ wide support to retain mask mandates is one factor that helped the country fight coronavirus variants despite the surge in cases.

“Even now people still feel naked without their mask when eating out, and I see people putting it right back when they go to get food in buffets. This gives us an extra layer of safety, which is always a good idea,” he said, adding that some still use face shields even if they are no longer required.

Having multiple vaccine types and eight brands are also factors as most countries only use two to three.

The United States of America, for instance, only has two mRNA types – Pfizer and Moderna – and one viral vector, Janssen.

“With the rise of variants, too much emphasis on spike protein increases the risk of antigenic escape. Despite the Western bias against Chinese brands, the inactivated vaccines (of Sinovac and Sinopharm) actually have more antigen epitopes aside from spike protein. This makes them more likely to be resilient to variant mutations,” Salvana said.

The Philippines was also one of the earliest countries to adapt boosters at three-month intervals.

Before the Omicron variant caused a spike in cases, Salvana noted the TAG and all experts group reviewed data and adopted the recommendation for booster shots.

“In addition, because of our vaccine brand diversity, many people ended up with heterologous boosters which may be more effective against variants than homologous ones,” he said.

The spike in cases in January was driven by the BA.2 sub-variant of Omicron, unlike the surges in other countries which had the BA.1 sub-variant.

“We saw mostly BA.1 among quarantined travelers, which means they didn’t make it to the community. Unfortunately, someone with BA.2 made it through. This resulted in a large spike but it also quickly receded. It probably ran smack into a boosted or recently vaccinated population,” Salvana said.

He added that the government’s preemptive lockdowns delayed the spike in cases caused by the Delta variant “so the hybrid immunity from breakthroughs from August 2021 was still relatively fresh”.

“We expect BA.2 hybrid immunity (BA.2.3 to be exact since BA.2 in the Philippines has been designated its own sublineage) to protect against other BA.2 sublineages, including BA.2.2 which is wreaking havoc in Hong Kong,” he said.

From March 7 to 13, there were only 4,131 new Covid-19 infections while intensive care unit bed utilization is at a mere 19.6 percent as of March 14.

A total of 64.5 million or 71.71 percent of target are already full vaccinated

Salvana cautioned that a spike is always possible so complacency must be avoided.

“In the meantime, enjoy your new-found freedom but don’t take it for granted. Keep masking up and vaccinating and we will be okay,” he concluded in his post. (PNA)