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December is typically when cases of influenza start to rise.
On Thursday, December 8, 2022, SciLine interviewed: Dr. Seema Lakdawala, an associate professor of microbiology and immunology at Emory University. She discussed topics including: how influenza spreads among people; historical trends for flu infections and deaths; how the COVID-19 pandemic has affected recent flu seasons; how this year’s flu season is going, and what researchers expect in the months ahead; and ways to block the spread of flu in communities and households.
SEEMA LAKDAWALA: My name is Dr. Seema Lakdawala. I am an associate professor at Emory University in the Department of Microbiology and Immunology. And I study influenza viruses and how they transmit through the air from person to person.
Interview with SciLine
How does influenza spread from person to person?
SEEMA LAKDAWALA: Similar to SARS-2 or COVID-19, we know that influenza viruses can transmit long range with small aerosols. They can also transmit short range with larger droplets. They can transmit through contaminated surfaces and through direct contact. All of these modes are possible and can lead to an infection.
What have recent trends taught us about how many people in the U.S. are infected by the flu, and how many people die?
SEEMA LAKDAWALA: Looking sort of historically over the past 10 years, we know that the annual burden of influenza is somewhere around 40 million infections a year. About 10 percent of those people will seek out some sort of medical visit, going to their pediatrician or an urgent care. And 10 percent of those individuals that seek medical assistance will become hospitalized. And 10 percent of that—somewhere around 25,000 people a year—will eventually die because of complications associated with the virus. So, that’s our annual burden of just seasonal influenza viruses. Those numbers can change if there was a new pandemic that emerges.
How has COVID-19 influenced recent flu seasons?
SEEMA LAKDAWALA: That’s been really dramatic, right? The last 2 years, when we had interventions around COVID-19, starting in March of 2020, we have seen a drastic decline in influenza cases and illnesses reported. So much so that we don’t even have a burden associated with the 2020-2021 season, because there were so few cases that season.
What do we know about how COVID and RSV are influencing this flu season?
SEEMA LAKDAWALA: What we know is that they’re not being exclusive such that transmission or spread of COVID isn’t excluding or causing interference between transmission of other pathogens as has been proposed. We know that all of them can co-circulate. What we aren’t seeing are individual people infected with multiple pathogens. We aren’t having people that are infected with COVID, and flu, and RSV. How they’re influencing each other is probably because we have all removed our masks. We are all back in school. Kids are in school. We are at work. People are travelling again, probably to similar levels as we traveled pre-pandemic or maybe even more. And there is an appetite to come back to some sort of normalcy. And in that vein, what happens is when we are all together in tight spaces interacting, and there is an individual who is sick, transmission can happen and can occur fairly efficiently. Especially because we haven’t been having immunity against these pathogens that we would normally see seasonally.
What do we know so far about flu infections and deaths for this flu season?
SEEMA LAKDAWALA: What we know so far is that there have been about 14 pediatric deaths from influenza already. We are way above our normal range for the past 11 years since we’ve been tracking flu—we’ve been tracking it for longer than that. But normally, we see peaks of influenza in January and February. We are well above that. We also had a very early season. About 9 percent of deaths right now are from complications associated with respiratory illnesses, either COVID or influenza, and so there is a lot of public health burden already associated this season.
What do researchers expect in the coming months of flu season?
SEEMA LAKDAWALA: We’re not seeing a drop off. We’re definitely seeing continued increase of cases each week. The CDC’s a couple of weeks behind. Looking at the case numbers from Thanksgiving, right around November 26th, you see the vast majority of the U.S. is in a very high influenza zone. Which means that the predominant, more than 25 percent of people being tested for influenza or respiratory illnesses, are positive. The other thing we expect is, given travel increasing for the holidays, that there’s likely to continue to be transmission of these pathogens.
Is there any information yet about the effectiveness of this year’s flu vaccine?
SEEMA LAKDAWALA: While vaccine effectiveness studies are ongoing, we tend not to get great interim results. What we do know is that the sequences that have been done for human infections so far are well matched to the vaccine strains.
What can be done to mitigate the spread of flu in communities and households?
SEEMA LAKDAWALA: One thing we learned during the COVID-19 pandemic is how to mitigate flu transmission. It was a drastic surprise I think for many of us the absolute absence of influenza during the COVID-19 pandemic when interventions were in play. What that means is that we have the tools to reduce the transmission of this virus already in hand. And some of those are increasing your ventilation when you’re at home or in buildings, hospitals, schools, to reduce long-range transmission. You can also put on a mask to reduce short-range transmission. And staying home when you’re sick. We are all very acutely aware of when we have any sort of respiratory illnesses now. And staying home at the sign of a tickle in your throat, and sneezing and coughing, and feverish feelings, is probably a good idea to reduce the spread of these respiratory viruses in the community. In addition, being—getting vaccinated is a really good way to boost your immunity against what’s circulating right now.
How can individuals mitigate transmission during holiday travel?
SEEMA LAKDAWALA: None of us want to go back to a scenario where we’re not able to see our loved ones during the holidays. But what we need to do is be mindful of ways in which we can reduce transmission within our communities and to our loved ones. So, what that means is, again, vaccination is a great strategy to reduce the susceptibility of individuals to become infected. And for you to reduce the amount of virus that you expel if you are infected with a breakthrough infection. Masking when traveling and masking when indoors is another effective way to reduce both expulsion of aerosols that contain virus, as well as inhalation of viruses. And finally, being mindful if you’re sick and avoiding contact with others when you are sick or taking extra precautions.
What has COVID taught us about preventing disease transmission?
SEEMA LAKDAWALA: What’s most important is that we remember that we have tools that can mitigate transmission of influenza already within our reach. We were—we proved that we can do this in the past 2 years. We just have to have the appetite to continue to do that. And that really comes down to being mindful, not being afraid to wear our mask again, and being thoughtful in our ventilation and the spaces that we attend.
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