November 20, 2023 – For those that received a flu shot this season, there's excellent news: This yr's formulation appears to be very effective in stopping severe cases and hospitalizations. This relies on the performance of the vaccine within the parts of the world where the flu season is coming to an end.
As flu season begins within the United States, health officials need to see how flu vaccines work in countries within the Southern Hemisphere, where flu season typically lasts from about April to September. A analysis A study published by the CDC that examined midseason flu data for South America showed that the flu vaccine there was greater than 50% effective at stopping flu hospitalizations.
But since that report was published earlier this yr, it has grow to be apparent that the vaccine utilized in South America has grow to be less effective because the flu season progresses. As a result, flu shots within the U.S. were updated to supply higher protection against versions of the virus that emerged toward the tip of the flu season in parts of South America where the information was collected.
“Final estimates can differ from preliminary estimates and it looks like – I was looking at some data from last season the other day – and it looks like the effectiveness probably decreased a little bit later in the season and that's exactly what's happening. “When we see changes in the circulating virus, which is most often a type called influenza A H1N1,” said epidemiologist Annette Regan, PhD, MPH, co-author of the CDC report on Southern Hemisphere flu. “It looks like we have updated the Northern Hemisphere wording based on this change.”
“It was a good report because it gave us an indication that the vaccine was working really well in the middle of the season, but when it's all said and done and we're at the end of the season, it doesn't always look the same. So we have a slightly different formulation in the Northern Hemisphere than in South America,” said Regan, who previously tracked flu data for the CDC and the Australian government. She is now an associate professor on the Orange County campus of the University of San Francisco.
Tracking flu trends below the equator helps medical teams and public health officials prepare for flu season within the north, although the influenza virus can change so well that predictions are helpful but not a guarantee of what's to come back, Dr. Paula Couto, an influenza surveillance epidemiologist on the Pan American Health Organization, a World Health Organization regional office for the Americas.
She said the interim report, which uses data from Argentina, Brazil, Chile, Paraguay and Uruguay, could help with preparation, for instance in estimating the necessity for health services this season and in addition the demand for antiviral drugs to treat the flu.
“Of course influenza is a tricky virus because it has pandemic and epidemic potential, so it's not necessarily the same thing [between hemispheres]”But that's why we're constantly monitoring and alerting ourselves to these viruses,” said Couto, who is also a co-author of the CDC report.
In the United States, there is not an official start date for flu season every year. The start date varies because it is usually set after the fact, based on a combination of factors such as increasing rates of positive flu tests and hospitalizations. This is usually the end of November.
“In the U.S., flu season tends to start in the Southeast, like Florida and Texas and surrounding states, and then the flu spreads from there,” Regan said. “Usually it doesn't take too long, we're talking a few weeks at most… because people move around a lot and are much more mobile these days than they were at the height of the pandemic.”
The US appears to be getting ready to flu season.
The CDC said flu cases are increasing within the Southeast and the South Central and West Coast states, in keeping with the agency's latest release weekly flu report. Currently, about 4% of flu tests nationwide are positive. One child has already died of flu. Children are one in every of the groups with low flu vaccination rates within the U.S. and world wide, Regan noted.
“I just don’t think any child should die from the flu, not in 2023 if we can prevent it,” she said.
The CDC recommends that everybody within the United States ages 6 months and older get vaccinated against the flu. After a vaccination, it takes the body about two weeks to provide enough antibodies for max protection, Regan said, and effectiveness typically lasts at the very least 4 months. That means now could be the time to get one as flu cases are on the rise.
About a 3rd of adults and youngsters within the United States have received the flu vaccination this yr CDC, which is several percentage points behind the previous yr. Adult vaccination rates vary from state to state, starting from 22% to 51%. The severity of flu season can vary, but federal data shows there are between 9 and 41 million cases annually, with as much as 710,000 hospitalizations and between 12,000 and 52,000 deaths.
Between October 1 and November 11 of this yr, the CDC Estimates that already existed within the USA:
- Between 780,000 and 1.6 million flu cases
- Between 360,000 and 770,000 flu doctor visits
- Hospitalization of 8,000 to 17,000 people
- Between 490 and 1,500 flu deaths
The COVID-19 pandemic disrupted seasonal flu trends and resulted in lower than normal numbers of flu cases when lockdowns and quarantines were common. Last winter, nevertheless, the flu returned with a vengeance. Both Couto and Regan said all indicators point to a return to normality this season.
However, the chance of great illness or death from influenza stays, particularly in high-risk groups comparable to very young children and the elderly. Regan urged people, even in the event that they have been vaccinated against the flu, to take other measures to forestall the spread of the flu, to guard themselves but in addition people who find themselves at high risk, comparable to grandparents or newborns.
Vaccines usually are not 100% effective, Regan said, so it's vital for people to scrub their hands and canopy their mouths when sneezing and coughing.
“And I think the most important thing is to stay home if we feel sick, especially because children are very good transmitters of influenza, there is good data for that. So keeping them at home when they're unwell can be really helpful in reducing the spread of influenza and RSV and stopping these epidemics,” she said.
Precisely because this flu season is a return to normality or goes in keeping with forecasts, the actions of every individual – from vaccination to washing their hands – are vital, Regan and Couto agreed.
“In the specific case of the flu, we know the next pandemic is going to happen,” Couto said. “You never really know when, and that's why it's important to be vigilant against influenza. “Of course, the last pandemic was COVID-19, but we must keep in mind that the flu continues to be a threat.”