CLINICAL MATTERS

The Christmas season in December also coincides with the start of the flu season in the Philippines. As the Amihan wind brings cooler temperatures, people tend to spend more time indoors and in close proximity to one another. This makes respiratory viruses much easier to transmit, and this is how the flu season has kicked off every year prior to the COVID-19 pandemic. Post-pandemic, two other viruses have now crashed the seasonal party and are currently co-circulating with influenza. RSV (respiratory syncytial virus) and the now-endemic SARS-CoV-2 both increase in incidence in parallel with the flu at this time of year, and this trifecta causes a lot of misery.

Among these three viruses, influenza is still the virus that is most familiar to everyone. Circulating influenza strains vary with each season. This results in more people being susceptible to infection since their antibody levels from the previous season have either waned or are not very protective due to the mismatch in antigens. Influenza can still be deadly to unvaccinated elderly and immunocompromised patients. The number of people who get sick each year is large enough to make a significant economic impact in terms of productivity and cause significant pressure on the healthcare system. There is only one locally available treatment for influenza. This is the oral antiviral oseltamivir. Oseltamivir is reasonably affordable but needs to be started quickly after symptoms start. Unfortunately, there is emerging resistance to oseltamivir and we will need other options to soon, such as inhaled zanamivir if resistance to oseltamivir continues to increase.

SARS-CoV-2 is now settling into a seasonal pattern and we have already seen a significant uptick in cases this December, even if there isn’t as much testing going on. New variants are constantly being generated, and the latest dominant variant is the recombinant virus known as XEC. XEC doesn’t cause more severe disease than previous variants, but it is more immune evasive and can be easily transmitted. This week alone, I had three new Covid-19 patients come to the hospital. Thankfully, two of the three patients weren’t very sick, and I was able to quickly send them home. The third patient is elderly and developed post-viral bacterial pneumonia after the initial bout of Covid-19 as a complication. While Covid-19 vaccinations have done a good job of decreasing mortality and morbidity, the continued evolution of SARS-CoV-2 variants and the unavailability of updated boosters in our country mean that more people will likely get infected before the season is over.

Treatment for Covid-19 is now routine for most doctors. People who are healthy and are not elderly typically do not require antiviral treatment. As long as they are fully vaccinated and received one or two boosters, rest and symptomatic treatment are sufficient to recover quickly. Elderly people and those with comorbid conditions can benefit from antiviral treatment to decrease their risk of hospitalization and progression to severe disease.

There are three locally available antivirals for moderate-risk Covid-19: nirmatrelvir-ritonavir (Paxlovid), molnupiravir, and remdesivir. The first two drugs are taken by mouth while remdesivir is given intravenously. Molnupiravir is not as effective as Paxlovid or remdesivir, with only a modest decrease in the risk of hospitalization and a shorter duration of viral shedding. However, it remains the cheapest option available. Paxlovid still has limited availability and is prohibitively expensive, costing up to ₱50,000 for a five-day course. Remdesivir costs about ₱10,000 for a three-day course, but the added hospitalization cost to give the intravenous drug can easily pass that of the total cost of a Paxlovid course. Severe Covid-19 is treated in the hospital with steroids and a five-day course of remdesivir. The bottom line is that while Covid-19 is more survivable than ever, it still entails a high cost, especially for the high-risk population of elderly people and those with comorbid conditions. 

Most people aren’t very familiar with RSV. Traditionally, it has been a more significant pathogen in the pediatric age group where it causes severe pneumonia in infants and toddlers. Surveillance data from the Department of Health shows that it has been circulating every year in the Philippines for several decades. RSV season has roughly coincided with the flu season since it is transmitted in the same way. We are now better able to diagnose RSV thanks to the availability of respiratory virus panels and multiplex antigen tests in hospital emergency rooms. This increase in diagnosis has also led to the insight that RSV is roughly two to three times deadlier than influenza, especially among elderly patients and those with comorbid conditions. This has led to the recognition that RSV is a significant cause of deterioration among patients who come to the hospital with pneumonia. Unfortunately, there are no effective antivirals for RSV. A monoclonal antibody known as nirsevimabis is effective as treatment among children and toddlers but is very expensive and is not available locally.

All three viruses are now actively circulating in the community and are causing a visible rise in respiratory illnesses. RSV has no available treatment, SARS-CoV-2 treatment can be prohibitively expensive, and flu treatment is in danger of emerging resistance. This means that the best option for controlling these viruses from a public health standpoint is still prevention. The cheapest, most effective way to decrease the risk of acquiring infection from respiratory viruses is still by wearing a medical-grade mask. This needs to be worn correctly and consistently, especially in areas with a high risk of acquiring infection such as crowded indoor spaces with inadequate ventilation. Masks both prevent infection in healthy people and transmission of infection from sick people. While there is no longer any mask mandate, high-risk populations like the elderly and those with comorbid conditions (and their household contacts) should seriously consider breaking out the masks every respiratory virus season. Surgical masks are more affordable and comfortable, but N95 respirators provide the best protection if worn correctly and consistently.

Another very effective prevention strategy is vaccination. All three viruses are now vaccine-preventable diseases. Influenza vaccination is given once a year to cover circulating strains and usually consists of three or four strains of the flu virus. Similar to Covid-19, flu vaccination is meant to prevent severe disease especially in the most vulnerable, but it still modestly decreases the risk of transmission. Flu vaccination is available from your doctor and many drug stores and is recommended for all ages. Covid-19 vaccination is currently not available locally.

Fortunately, the initial series and previous boosters continue to protect against severe disease even with the most recent variants. Three manufacturers are making updated vaccines yearly and it is hoped that at least one of these companies will bring in their latest updated SARS-CoV-2 vaccines to the Philippines. Finally, RSV vaccination is now available for elderly adults to prevent severe disease. There are two kinds of RSV vaccines, one that is already being marketed and another slated for early next year. A recently published study showed that RSV vaccination in adults 60 years and above, regardless of brand, significantly reduced hospitalization and severe disease by over 80 percent during the October 2023 to March 2024 flu season in the US.

This holiday season, make sure you protect your loved ones by wearing masks and asking your doctor about respiratory virus vaccination. After all, we all want to give and receive good gifts, and not bad viruses for Christmas