CLINICAL MATTER

Is it really over? One month after the lifting of the state of emergency due to the Covid-19 pandemic in the Philippines, many people continue to wear masks. Perhaps the reemergence of influenza and other viral respiratory infections has made people realize that masks are valuable against many other things beyond Covid-19.

Flu and milder upper respiratory tract infection viruses are still a nuisance and can make people miss work and feel miserable. In the meantime, the WHO has designated EG.5 as a variant of interest and BA.2.86 as a variant under monitoring. Should we be concerned? Will we need to reimpose mask mandates and social distancing?

Let’s review the Covid-19 variant designations. Whenever a new variant emerges with mutations that can potentially increase the risk of immune escape, the WHO keeps a closer eye on it. During this stage, it is designated as a variant under monitoring or VUM while more evidence is gathered on whether these mutations translate to a real-word growth advantage. If the VUM continues to increase in proportion among circulating variants and shows definitive signs of immune escape, it is elevated to a variant of interest (VOI) and closer monitoring continues. A VOI is elevated to a variant of concern (VOC) if it is assessed, with a moderate to high degree of confidence, to exhibit at least one of these characteristics: an increase in clinical disease severity, increase in cases sufficient to potentially overwhelm the healthcare system necessitating lockdowns or other major public health interventions, or a significant decrease in the effectiveness of current vaccines to protect against severe disease.

Whatever new SARS-CoV-2 variant emerges, barring a truly awful VOC, there will always be some degree of immunity as a result of widespread vaccination and infection. This means that the death rates we saw back in 2020 are a thing of the past, and even the worst new variant is unlikely to approach that level of devastation. Partial immunity is enough to attenuate most cases of severe disease, even if mutations result in substantial increases in infection rate. The availability of effective treatment, including steroids and antivirals, is another layer of protection that ensures we won’t have a repeat of the pandemic catastrophe.

Even with a perceptible decrease in masking and the entry of EG.5 in July, there have been hardly any increase in cases or hospital admissions locally. It is true that fewer and fewer people are testing for Covid-19, but even if we don’t capture this increase, any increases in severe disease will have an impact on hospital capacity. So far, there is no such rise in hospitalizations. 

There is no evidence that EG.5 causes worse disease or causes any difference in symptoms. The designation of EG.5 as a VOI is because of its growth potential and immune escape characteristics. There are some indications that it is may increase the incidence of disease in the short term. The overall public risk assessment of WHO, however, is that the public health risk of EG.5 is low. EG.5 is causing increases in cases in some countries, particularly the US, where very few people still wear masks. In response, some US hospitals have reinstated their mask mandates for staff, patients, and visitors. The fact that we aren’t seeing this rise locally shows that the decision of many Philippines hospitals to keep mask mandates on their premises is a wise one.

BA.2.86 has not been detected locally as of this writing. It has been designated as a variant under monitoring by WHO primarily because of the number of mutations—at least 30—and the fact that it has been found in many places that are far apart. It is still too early to tell whether it truly has a growth advantage at this time, and there is no evidence it causes more severe disease.

Many of the vaccine manufacturers are currently working on updated vaccines. Moderna and Pfizer are targeting a rollout date of September for their most updated vaccines. These vaccines will no longer be bivalent, but instead contain only one variant (updated monovalent), which will most likely be XBB or one of its sublineages. 

To review, the current bivalent vaccines are made up of a mixture of the spike protein of the original Wuhan virus and the BA.4/BA.5 variant. The reason BA.4/BA.5 are lumped together is because while there are genetic differences between BA.4 and BA.5 in their respective genomes, their spike protein sequence is identical. BA.4/BA.5 are Omicron sublineages while XBB is a recombinant virus of two Omicron sublineages. 

The reason the original Wuhan virus lineage will no longer be included is that there does not seem to be any evidence it adds any further protection as part of a booster dose with the current circulating variants. Old monovalent vaccines based on the original Wuhan lineage can still be used as a primary series vaccination and do continue to protect against severe disease. These are being phased out, however, in favor of the current bivalent vaccines which have also been approved for primary series vaccination in the US and many other countries.

As more bivalent vaccines arrive, it is recommended that anyone above the age of 12 who has not gotten a bivalent booster should get one. This is regardless of how many monovalent boosters they have received, as long as the last monovalent booster dose was given at least two months ago. Getting the bivalent vaccine as a “top-off,” especially for the vulnerable population gives significant additional protection against severe disease and decreases the risk of hospitalization. 

There is currently no estimate as to when the updated monovalent boosters will be available in the Philippines. The ones who will most likely benefit from this updated shot will still be the vulnerable population and the healthcare workers. There are other types of vaccines in the works and it remains to be seen if these have improved efficacy against infection and transmission against the circulating variants. In the meantime, there are two important things you can do to maximize your protection: Get your bivalent booster if you haven’t done so and, as always, wear your mask.