Transitioning to endemicity and the next generation of vaccines

Why we shouldn’t worry about the rising Covid-19 cases

Even as case numbers continue to rise in the Philippines as BA.4 and BA.5 work their way into the community, there is no parallel increase in the number of severe and critical cases being admitted into the hospitals.

While increasing case numbers are inevitable as we continue to open our economy, the impact of these cases is no longer the same as they were two years ago.

With more than 70 million Filipinos fully vaccinated and a boosting program in place, there is good reason to hope that the worst of the pandemic is finally behind us. Despite decreasing vaccine efficacy against infection with BA.4 and BA.5, the latest scientific data shows that our current vaccines when boosted continue to protect against severe and critical Covid-19. This ensures that even if new Covid-19 cases climb up into the tens of thousands, there will be much less of an impact on hospitalization.

If this scenario sounds familiar, it is because this is the same situation we go through with influenza every year.

We do not test everyone we suspect has the flu, nor do we keep a running count of cases except perhaps those who are hospitalized. The same will eventually happen with Covid-19 as it transitions into endemicity. This means that metrics like two-week growth rate and positivity rates are becoming less and less meaningful.

As we become more selective with testing, the positivity rate is expected to be higher because only those suspected of having Covid-19 will be tested. This results in selection bias and a small denominator as mild and asymptomatic cases are less likely to undergo RT-PCR testing.

World Health Organization (WHO) has not yet declared the acute phase of the pandemic over.

There is a Technical Advisory Group that meets every three months or so to determine whether it is time to do so. Since WHO has to consider global trends, some countries may already be in the endemic phase even as others are not. Some countries have already declared endemicity since they no longer feel any restrictions are justifiable with the current low fatality rates and availability of effective vaccines and medication.

A look at our latest weekly case report is instructive. The one released last June 27, 2022 (figure on page 3) shows that despite daily cases increasing by 53 percent from the week before, the number of new severe and critical cases went down from 15 to 14 cases. Healthcare utilization remains at 18 percent for non-ICU and 14 percent for ICU, very far from a moderate risk healthcare utilization rate of 50 percent or above. Out of the 51 newly reported deaths, none were from the last four months. These reported deaths were all just backlogs with some going back as far as February of last year. Finally, more than 70 million people have been fully vaccinated.

While first booster rates are at just under 15 million, there is anecdotal data that many more people have surreptitiously taken second courses of vaccines and so are double boosted. This is difficult to capture as it is a violation of regulations and cannot be officially reported on the vaccination certificate. Nevertheless, this is a factor in the presumed poor uptake of first boosters since these people would already be getting a fifth dose if they got the first booster. Unfortunately, many chose to ignore the advice of the government and jumped the gun on the second course of vaccines. This could have been unsafe and may not be properly timed. Nevertheless, the incoming administration has to try to account for these people when setting their first booster targets.

New data looking at vaccine efficacy against the new Omicron sublineages is mixed. While there is a clear decrease in the ability of vaccines to protect against infections from Omicron, the boosting data clearly shows that these continue to work effectively against severe disease and hospitalization. Unfortunately, many countries have already removed their mask mandates. This has already led to significant increases in cases as a result of the higher transmissibility of BA.4 and BA.5 and the decreased neutralizing antibody activity of our current vaccines. We are fortunate we continue to wear masks in the Philippines. This is the reason we are seeing a very gradual increase in cases despite the entry of BA.4 and BA.5. The next administration should maintain mask mandates until such a time when we have high first booster rates.

One major development is the formulation of Omicron-specific vaccines. Pfizer and Moderna have announced BA.1 containing vaccines, and other manufacturers are starting to update their vaccines as well. Preliminary data shows that the Moderna bivalent vaccines which include the ancestral SARS-CoV-2 genetic material along with Omicron-specific spike protein mRNA sequences significantly increase neutralizing antibody activity against Omicron when used as a booster. Clinical trials may still need to be done to see if this in vitro data translates to decreased rates of clinical transmission and infection, but the antibody data is promising. There is also the possibility that regulatory authorities treat these reformulated vaccines as they do with influenza vaccines which are updated every year and do not require new trials since it is essentially the same vaccine with strain-specific modifications. If the latter scenario occurs, updated vaccines could be available for public use as soon as September or October of this year.

While waiting for these updated vaccines, we need to improve first booster uptake as this remains an effective strategy for mitigating the decreased efficacy of the primary series against Omicron.

The upcoming boosting of adolescents is very welcome and will add to the immunity pool. Second boosters for vulnerable groups are allowed and may need to be pushed further in light of increasing cases. Second doses for the rest of the population are still largely unsupported by hard data, and it may be better to give the updated vaccines to these populations once they are available.

Also, the to-do endemicity list is for the vaccine manufacturers to obtain a Certificate of Product Registration for their vaccines so that private physicians can start sharing the task of vaccinating the public. This will also ensure the continued availability of vaccines once the state of public health emergency ends. The EUAs are only valid while the state of emergency exists and this declaration will expire in September 2022, if not terminated earlier by the new administration.

In its final meeting, the IATF removed the two-week growth rate as a metric for the alert level system. This reflects the situation on the ground that even with increasing cases, there is little pressure on the healthcare capacity. This is just a preview of what endemicity will look like. With these updated metrics, we will not have to escalate to Alert Level 2 despite any number of cases in the community, as long as the healthcare utilization remains below 50 percent. This modification can be safely made because the Duterte administration has already ensured that the Philippines have weathered the worst of the Covid-19 pandemic through vaccination. We wish the incoming government success in guiding our country towards recovery and endemicity, and we as a people should do our part in helping this come to pass.

While increasing case numbers are inevitable as we continue to open our economy, the impact of these cases is no longer the same as they were two years ago.