Waning efficacy

SKETCHES - Ana Marie Pamintuan - The Philippine Star

Many people I know are now looking at their COVID vaccination cards – not just for discount eligibility in commercial establishments, but also to remember the date of their second dose.

They then compute six months from the date, so they can take extra precautions against infection and plan for getting a booster shot.

Like it or not, enough vaccines or not, people are now discussing options for getting third doses or boosters against COVID-19. Those with the means are planning trips to the United States to get their boosters with the vaccine brand of their choice.

This is because of reports from other countries led by Israel about the waning efficacy of even the top-of-the-line jabs, Pfizer-BioNTech and Moderna, which provide the scientifically proven highest protection against COVID.

Our own experts themselves, who are monitoring studies and actual experience in Israel and other countries about the efficacy of the different COVID vaccines, are now saying that a third dose or booster is needed six to eight months from the second dose (or from the first and only for the single-shot J&J Janssen jab).

Naturally, concern is highest among those who were first in line for vaccination in our country: the health frontliners, who got their full two doses in March. Their six months ended in September.

The elderly and those with comorbidities followed, with their vaccination schedules even overlapping with those of the healthcare workers. For the A2 and A3 groups, vaccine efficacy is also waning. This could be a factor in recent reports about fully vaccinated seniors, including those without comorbidities, catching the virus and landing in the ICU or even succumbing to COVID.

So people are worried. Some in the vulnerable groups have already received boosters, mostly courtesy of certain private entities.

The government itself is preparing to give health frontliners booster shots beginning this month, and third doses to the immune compromised. This couldn’t come sooner for the health workers; Indonesia did it last August for its health frontliners, who were vaccinated mostly with Sinovac. Singapore and Thailand started administering boosters in September; Malaysia began last month.

I don’t think anyone will begrudge health frontliners the shots, even if about three-fourths of the country’s vaccine-eligible population has not yet received even a first dose. As it is, hospitals are already bemoaning their growing lack of healthcare workers. It is in the national interest to keep all HCWs safe from COVID and healthy enough to attend to the sick.

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A third dose is given to those for whom the full two doses aren’t enough to give the safe level of immunity – the infirm elderly and those with comorbidities, and health frontliners with high exposure to the infected.

On the other hand, a booster is given to younger, healthier people whose vaccine efficacy is naturally waning over time.

Rontgene Solante, infectious disease doctor and a member of the country’s vaccine expert panel, says the period of efficacy of the jabs will remain the same regardless of whether the recipient has had COVID.

What hasn’t been fully established is whether the natural immunity from a previous bout with COVID will still provide some protection once vaccine efficacy has waned.

The natural immunity is uncertain. Some of those infected with the original SARS-CoV-2 strain suffered return bouts during the two surges this year fueled by the more infectious Alpha, Beta and Delta variants.

But there’s also a theory that the more serious the infection, the greater the immunity for survivors. Can such survivors afford to worry less about their vaccine efficacy waning?

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Besides worrying about waning jab efficacy, people are also wondering about the safety of mixing and matching vaccine brands for their boosters or third dose.

Solante assured “The Chiefs” on One News last Monday that all vaccine brands used in the country have been vetted for safety.

The government is still studying the safety of mixing and matching brands, with the study outcome expected next year. But other countries have gone ahead and shown generally positive results when mRNA vaccine brands are used as boosters or third doses for other mRNA jabs and Sinovac.

As in the start of the vaccination program, those with brand preference are the most concerned about the mix-and-match policy.

Most of those with brand preference got the Western jabs: Pfizer, Moderna, AstraZeneca, J&J. They don’t want their booster to be the China-made Sinovac or Sinopharm jab. They worry about mixing and matching cutting-edge mRNA vaccines with jabs developed using the traditional technology.

Solante told us that based on their observations, the drop in efficacy over time was greater for Sinovac recipients compared with those who got the Pfizer shot. But this is not unexpected; it has long been scientifically established that the Pfizer (and Moderna) vaccines had higher efficacy than the ones made in China.

Sinovac Biotech, which is recommending a booster for its CoronaVac after six  months, of course says its own product provides the optimum third-dose boost for its vaccine.

As I have written, I have confidence in Chinese medicine, and I won’t mind getting my full two-dose Sinovac shot boosted with the same brand when the six months are up. But neither would I mind getting Moderna as booster, since it reportedly has the highest efficacy against the Delta variant.

What I would avoid is the Pfizer jab, became of my high risk for severe allergic reaction to certain drugs.

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The need for boosters and third doses could complicate economic reopening. The OCTA Research Group, which is supporting the easing of Metro Manila to Alert Level 2 because of the significant slowdown in infections, is at the same time warning against complacency amid reports of breakthrough infections and the waning efficacy of vaccines.

A surge is still possible, OCTA warns, especially if there are super spreader events during the holiday season and the election campaign.

The Department of Health yesterday warned of another case spike as it noted a slowdown in the decline of infections.

University of the Philippines political science professor Ranjit Rye, seen as the wet blanket in OCTA, reiterated to The Chiefs last Monday his constant warning about “overestimating achievements and underestimating the virus.”

Having seen the unpredictability of this lethal virus, it’s a warning that is prudent to heed. Even if we get our boosters.

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