Should we be scared of the 'superflu'?

 

A look into the different types of flu to watch out for

By Dr. Edsel Salvana

Published Jan 19, 2026 08:37 am

At A Glance

• We should use this opportunity to educate people about the importance of the yearly flu shot in keeping everyone healthy.
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After an early start to the flu season, various public health authorities, including the US Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), have reported the detection of a new dominant flu strain. This strain, with the very technical-sounding name of influenza AH3N2 subclade K, is a variation of the usual seasonal flu strain AH3N2 with some new mutations. Unfortunately, based on anecdotal reports that some people felt much worse than usual, the new virus was quickly dubbed by the media as the “superflu.”

This had the effect of sensationalizing the news of a new strain. More than a few social media posts claiming this could be a new pandemic went viral (no pun intended). Even when scientists countered that it doesn’t seem to be very “super” at all, fake news continues to spread. What are the facts about influenza AH3N2 subclade K, and is there any reason to worry?

The influenza virus is a shapeshifter by nature. It comes in four antigenic variants: influenza A, B, C, and D. Two of these antigenic variants, specifically influenza A and B, cause most cases of flu in humans. Influenza A is responsible for previous pandemic outbreaks, including the notorious AH1N1 Spanish flu in 1918, which affected nearly 1/3 of the world’s population, and the more recent AH1N1 Swine flu pandemic in 2009.

The influenza virus genome consists of eight segments of single-stranded RNA. RNA viruses such as influenza, HIV, and SARS-CoV-2 are more prone to mutations compared to DNA viruses. Genetic changes in influenza A can happen through spontaneous mutations from these errors and also through another mechanism known as recombination.

Spontaneous mutations are usually introduced by errors in copying when viral RNA is duplicated. These mutations occur at random, and most of the mutations that occur are silent or might even be harmful to the virus. Occasionally, these mutations can affect the proteins on the viral surface and decrease the ability of our body to recognize the virus. This process is known as antigenic drift, and immune escape in this case is gradual.

Recombination occurs when two or more virus strains infect the same cell and end up mixing their different segments of RNA together. This can cause a more drastic genetic change, and the process is known as antigenic shift. Antigenic shift can occur between influenza A viruses from different host animals and give rise to a novel pandemic virus to which humans have little or no immunity.

For example, influenza A viruses that infect birds can cause more severe pneumonia in humans. It is, however, very difficult for humans to get infected with avian flu due to the less efficient binding of the virus with proteins in the upper airways of humans. If an avian influenza virus combines with a human influenza virus, it may result in a virus that causes more severe disease than regular human influenza and is more transmissible than avian flu. The 2009 AH1N1 swine flu was an antigenic shift phenomenon where genetic material from different swine influenza viruses got mixed together and resulted in a highly transmissible virus. While the 2009 AH1N1 influenza virus did not cause more severe disease, there was almost no immunity to it at the outset due to the radical change in its genetic signature, causing it to spread quickly.

The new influenza AH3N2 subclade K is believed to be the product of antigenic drift. It is a direct descendant of influenza AH3N2 subclade J.2.4 with added mutations, so it is technically also subclade J.2.4.1. The new mutations seem to decrease the effective immune response of the body against the virus based on animal serum studies. This may have given it a survival advantage that is consistent with the increasing numbers of influenza AH3N2 subclade K being detected as a proportion of the circulating influenza viruses. Based on early studies, these genetic changes don’t seem to have significantly affected the effectiveness of the current vaccines. The current flu season vaccine is still protecting against severe disease and hospitalization. There is also no evidence that influenza AH3N2 subclade K causes more severe disease when confirmed genotyped cases are compared to other circulating strains.

Just how much the new influenza AH3N2 subclade K mutations are enabling immune escape is not yet clear. There are a lot of confounding factors. Many parts of the world had an early start to the flu season. This means that the number of flu cases is peaking earlier. Therefore, when compared to the same time frame as previous years, the case counts for this year would be higher earlier in the season. Another major confounder is that, compared to other years, there has been very low flu vaccine uptake, which, as we would expect, results in more cases of flu and more severe symptoms in unvaccinated persons.

There is currently limited flu vaccine availability since the flu season is already well underway. The Southern Hemisphere vaccine, however, should be available by around February. We get availability for both Northern and Southern Hemisphere vaccines in the Philippines six months apart. We only need to get one vaccine shot once a year, so if you haven't gotten it in the last year, you can get it soon when it becomes available.

In the meantime, you can protect yourself and others by wearing a mask, especially if you are in the vulnerable population or if you are living with someone who is elderly or immunocompromised. Stay home if you have flu symptoms and talk to your doctor if you get sick. Proceed to the ER if you have warning signs, like shortness of breath or low oxygen levels (

The bottom line is that the “superflu” does not seem to be very super at all, and there is no reason to believe it will cause another pandemic. The observation, however, that fewer people are taking the yearly influenza vaccine is very troubling, and this will result in more cases of severe influenza and deaths from the virus. It is important to treat the emergence of influenza AH3N2 subclade K as a warning that the virus continues to mutate. We should use this opportunity to educate people about the importance of the yearly flu shot in keeping everyone healthy. As a bonus, a higher vaccination rate means fewer cases and fewer chances for the virus to mutate, and it might just head off the next influenza pandemic.

Facing the HIV crisis in the Philippines

 A story of advocacy, molecular detective work, and resilience

By Dr. Edsel Salvana

Published Sep 1, 2025 11:17 am

At A Glance

I started to see an increasing number of HIV patients with opportunistic infections. These were mostly young men in their 20s, and they were dying from AIDS-related illnesses.

Last week, I was asked to present our work on HIV at the Paul Galkin Global Health Grand Rounds at the William Alpert School of Medicine at Brown University. Brown University, located in Providence, Rhode Island, is one of the eight storied Ivy League universities, which includes Harvard, Yale, Cornell, Dartmouth, Columbia, Princeton, and the University of Pennsylvania, that are some of the most exclusive schools in the world. Getting invited to a named lecture at any reputable university is a prestigious honor. Getting invited to a named lecture at an Ivy League school is career-defining.

I was invited to give the talk because of the impact my work on HIV has had in the Philippines. The person who nominated me for the talk was Dr. Susan Cu-Uvin, a world-renowned HIV researcher and infectious diseases physician at Brown University. Dr. Cu-Uvin was originally from the Philippines, but she was recruited as a Brown faculty member after training at Brown as a fellow in the 1990s. She has had a long history of collaborative work with the University of the Philippines (UP). When I returned to the Philippines in 2008 after specialty and subspecialty training in the US, Dr. Cu-Uvin was already engaged in different training programs for UP Manila faculty, even as she did high-level cutting-edge work on HIV in women. Our work frequently intersected, and I have participated in some of the training grants she received, including the Brown International Advanced Research Institutes in 2012, where I came to Brown for a two-week intensive training program in HIV. This experience helped me design the research projects I eventually undertook. I ended up looking at the molecular epidemiology of HIV in the Philippines, which we eventually found played a major role in the increase in cases. The Paul J. Galkin Global Health Grand Rounds is an endowed lecture series that highlights collaborations between Brown faculty and their international collaborators, and Dr. Cu-Uvin thought the work we were doing was worthy of being presented.

This was my third time visiting Brown University. It is located in the city of Providence in Rhode Island. Rhode Island is the smallest state in the US, and was founded in 1636 as a haven for religious freedom. It has a long history of tolerance and was one of the 13 founding states. Famous Brown University alumni and professors include 11 Nobel Prize winners, as well as philanthropist John D. Rockefeller Jr. and actress Emma Watson. Aside from Brown University, another notable educational institution is the Rhode Island School of Design (RISD), which is one of the top design schools in the world. Among their Filipino alumni is the late Carlos Celdran, who was a multidimensional artist and did innovative and thought-provoking tours of Manila.

The lecture started with a sumptuous Filipino dinner. Dr. Cu-Uvin spoke first, tracing her journey from the Philippines to Brown and showing the many collaborations that she enabled and fostered during her tenure. I was then asked to speak about my HIV work.

My talk was entitled “HIV Crisis in the Philippines: A Story of Advocacy, Molecular Detective Work, and Resilience.” In the early 2000s, there was not much HIV in the Philippines. It was described as “low and slow,” and it was a mystery why this was the case when our other sexually transmitted infection rates were similar to those of different countries around the region. While I was doing my infectious diseases fellowship at Case Western Reserve in Cleveland, I was trained to treat HIV, but I did not think it was important since we (my wife and I) planned to return home after we completed our training. I instead decided to focus on tropical medicine, which I thought was more relevant to our country. Unfortunately, when we returned home and joined the Philippine General Hospital, I started to see an increasing number of HIV patients with opportunistic infections. These were mostly young men in their 20s, and they were dying from AIDS-related illnesses like cryptococcus meningitis, pneumocystis pneumonia, and disseminated tuberculosis. I immediately changed my focus from tropical medicine to HIV, and we started a media campaign to increase awareness.

We were able to raise money to purchase a CD4 machine for our HIV clinic, and we ramped up publicity on the surge of cases. In the meantime, I was wracking my brains as to what had changed such that cases would suddenly start rising just like that. When I was at Brown in 2011, I heard a lecture from Dr. Rami Kantor on how some HIV subtypes behaved differently from the usual HIV subtype B that is seen in developed countries. This caught my attention, and I found there was very limited data on HIV subtypes in the Philippines. Using our own laboratory funds and later on with grants from the Department of Science and Technology, we showed that the rise in cases was being fueled by a more aggressive and transmissible HIV subtype CRF01_AE that is more commonly seen in Thailand. Our work showed that the predominant Philippine subtype had changed from subtype B to CRF01_AE at the time the cases were rising, and this significantly drove transmission. We also did seminal work on HIV drug resistance, which influenced government policy in procuring more effective antiretroviral agents for Filipinos living with HIV.

Finally, we developed a portable HIV drug resistance test that is half the cost of conventional HIV drug resistance testing with much fewer technological requirements. This won the Innovation of the Year award from the Infectious Diseases Society of America Foundation in 2023 during IDWeek in Boston, US, and the test is slated for clinical validation in 2026 with funding from the Philippine Government. This test has the potential to transform the treatment of HIV globally and will better inform treatment decisions, as well as being useful in surveillance for emerging resistance. I ended the lecture by going back to one of my patients who is still alive today because of life-saving antiretroviral treatment. I emphasized the fact that at the end of the day, our successes and failures shouldn’t just translate to academic achievements and published papers but should have a real impact on the lives of our patients.

Preventing the next wave of respiratory infections

Viruses such as influenza and SARS-CoV-2 don’t stand still. They constantly mutate and the more hosts they infect, the more likely they are to stumble onto a serendipitous mutation.

BY DR. EDSEL SALVANA

Jul 19, 2023 08:32 AM

  

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AT A GLANCE

• One major intervention that has finally been scientifically proven is the efficacy of masks in preventing infection.

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As the Covid-19 pandemic transitions into endemicity, it is important to remember the lessons of how a tiny microbe can wreak so much havoc. With nearly seven million confirmed deaths and perhaps more than double that in unconfirmed ones, SARS-CoV-2 has taken an immense and bloody toll on humanity.

In addition, it has had a catastrophic impact on long-term health, mental well-being, and the economy. Even as we celebrate the lifting of the pandemic emergency, the seeds of the next pandemic are already scattered and sown. It is not a question of if, but when.

So, what’s the best way to protect ourselves from respiratory viruses? Same way we protected each other from Covid-19—the PDITR strategy, which stands for prevention, detection, isolation, treatment, and reintegration. Put another way: Wear a mask, vaccinate, stay home if you are sick, and talk to your doctor. The application of these measures is not as draconian as that of Covid-19, but will have a significant impact on influenza, (endemic) Covid-19, and other respiratory viruses moving forward.

One major intervention that has finally been scientifically proven is the efficacy of masks in preventing infection. It is ironic that now that we have an effective intervention, it is also when most people just want to get rid of their masks and no longer test for illness. Viruses such as influenza and SARS-CoV-2 don’t stand still. They constantly mutate and the more hosts they infect, the more likely they are to stumble onto a serendipitous mutation that can make them more transmissible or deadly.

During the pandemic, there was a lot of acrimony regarding which mask was most effective. We now know that any mask is better than no mask at all. N95 respirators remain the best for preventing infection, but even surgical masks when worn consistently and correctly can approximate the protection of higher quality respirators. We now also know that aside from Covid-19, these masks work to prevent other respiratory diseases, including influenza and the common cold.

The original (or “OG” as young people say nowadays) pandemic organism—influenza—is already starting to make its appearance this year. Thanks to the wider availability of molecular testing, it is now easier than ever to check if someone has the flu. I’ve had three patients in the hospital test positive for influenza A while undergoing a respiratory panel test to check for Covid-19 this week alone. One patient has already died and I believe that his concurrent influenza infection made his prognosis worse. All these patients tested negative for Covid-19, the suspicion for which was the reason they underwent testing in the first place.

This is why the US CDC is encouraging multiplex (multiple organisms at a time) testing based on the presence of symptoms. A cold and a fever can be from any respiratory virus. Whether it is a coronavirus or an influenza virus, it is important to track small outbreaks like these since they can represent the tip of the iceberg of ongoing community transmission.

Multiplex molecular testing also helps us avoid the unnecessary use of antimicrobials since it tells us what specific virus is causing an illness and some multiplex tests can concurrently test for common bacteria that cause pneumonia.

For instance, a positive influenza A test and a negative Covid-19 test means we can confidently do away with molnupiravir or nirmatrelvir-ritonavir (Paxlovid) and use oseltamivir instead. A positive influenza A test can explain a high fever in someone with respiratory symptoms and a doctor is less likely to prescribe antibiotics, unless there are other indications of bacterial infection.

Unfortunately, molecular testing remains expensive and needs a sophisticated laboratory to run the tests. Perhaps multiplex antigen testing, which is much cheaper and easier to perform, will be the next innovation. We already have separate Covid-19 antigen and influenza antigen tests but understandably not very many people want their noses poked twice. With hope, the diagnostics revolution that Covid-19 inadvertently forced upon us bears fruit downstream and rapid testing will become affordable and ubiquitous for all manner of respiratory pathogens.

The unprecedented vaccination campaign for Covid-19 has opened our eyes to just how important vaccination is not just for children but for the adult population as well. Yearly influenza vaccination has never been popular in the Philippines, but the data backing up its benefits is very solid. Like Covid-19 vaccines, influenza vaccination isn’t very good at interrupting transmission or preventing illness. But similar to our Covid-19 vaccines, influenza vaccination is very effective at preventing severe disease, especially in the most vulnerable. Influenza vaccination can decrease the risk of an elderly person ending up in the ICU by over 70 percent.

Other adult illnesses like pneumococcal pneumonia and herpes zoster are likewise vaccine-preventable and we should all take advantage of these vaccines to safeguard our health. Bivalent Covid-19 vaccines are already being rolled out and those who qualify should avail of these as soon as possible. Further Covid-19 boosters downstream are still up in the air but it is important to stay up to date on these by talking to your doctor.

Quarantine and isolation were among the least popular measures during the pandemic. In fact, many people nowadays are not testing for Covid-19 because they know they’ll be obliged to isolate.

In general, if someone has respiratory symptoms, it is prudent to isolate at home for a few days if possible to prevent the spread of infection. Even if a test isn’t done, wearing a mask if you have recently been sick can help mitigate viral transmission, whether it is Covid-19, influenza, or something else. “Reverse isolation” of vulnerable household members along with masking can also help mitigate severe disease among the elderly and the immunocompromised.

As Covid-19 becomes just one of many respiratory viruses circulating in the community, it is prudent to mitigate the impact of these pathogens by repurposing the tools that worked so well during the pandemic. This will go a long way toward decreasing the risk of community outbreaks of not just Covid-19 but also of influenza and other viruses of pandemic potential.

But since we are no longer living in a health emergency, the government is no longer requiring adherence to minimum public health standards. It will have to be a personal choice to protect yourself and to protect others with the choices we make on a day-to-day basis.
With hope, we all make the right choice.