Experts have predicted that the 2019/20 flu season in the Northern Hemisphere will be a bad season. And it wasn’t.
With the COVID-19 pandemic hit, the suspension of international travel, physical distance and wearing masks becoming more common, the flu is gone.
“There was a clear drop-off when the blockade was announced,” said Dr. Rachel Baker, who studies public health and infectious diseases at Princeton University’s High Meadows Institute for Environmental Studies, in mid-March 2020. This was especially noticeable in tropical places like Hawaii. In Hawaii, cases usually persist throughout the year, rather than alternating seasonal peaks with zero cases.
Part of the sudden decline may be the result of health authorities in some areas paying all attention to COVID-19 and essentially not testing it. influenzaSaid Dr. John McCaulejye, director of the Worldwide Influenza Center at the Francis Crick Institute in London, one of the six influenza monitoring centers in the World Health Organization’s Global Influenza Monitoring and Response System.
More Americans have opted to be vaccinated against the flu in the 2019/20 season, according to Centers for Disease Control and Prevention.. The rate increased by 3.1 percentage points, with 48 percent of adults vaccinated. However, vaccination rates for children remained the same.
Obviously, health measures designed to delay the transmission of COVID-19 are as effective as reducing the spread of influenza and other infections. Respiratory tract infection..
Baker and her colleagues have COVID-19 precautions 20% drop A respiratory syncytial virus (RSV) infection nationwide last spring may have had a similar effect on influenza.And this may be an underestimate Another study After the introduction of public health measures from Hong Kong, influenza transmission has decreased by 44%.
“This is one of the clear signals that these interventions work,” Baker said. “It’s very efficient at stopping the spread of these viruses.”
This year is “significantly different”
The situation this year was “significantly different,” Baker said, with no influenza outbreaks in the Northern Hemisphere during the winter of 2020/21.
“There was no speaking influenza season in the Southern Hemisphere,” added Dr. Ian Barr, Deputy Director of the WHO Collaborative Research Center for Influenza at the Peter Doherty Institute for Infectious Immunology in Melbourne, Australia.
This has made things difficult for professionals like Bar and Macquarie who contribute to the global plan for which strains of influenza should be included. Seasonal influenza vaccine. The decision becomes more complicated if there is a lack of information about which strains are circulating in the population.
And it doesn’t seem they didn’t see.
“We scrutinized the planet to find out where the virus was,” Barr said. Overall, more samples were tested this year than last year, but few flus were found.
There were minor outbreaks in Bangladesh, India, Southeast Asia, West Africa and Europe, but that was all. As a result, the WHO team faced a dilemma when developing the 2021/22 vaccine for the Northern Hemisphere. Vaccine strains should be kept the same. Suppose the circulating strain returns before the pandemic ends. Is it to reflect what they have seen in a few around the world?
The team would have wanted to have more data to make difficult decisions, McCawley explained. But in the end, they chose to continue the course.3 out of 4 stocks 2021/22 vaccine It will remain the same as last year’s Southern Hemisphere version. They turned only one (H3 influenza A-share) into a circulating one.
It is unknown what will happen next.
Next year’s outbreak
Modeling shows that as the population’s immunity weakens during the “missing season,” life is likely to return to normal and outbreaks are more likely after the public health measures implemented during the pandemic have been mitigated. There is a possibility of becoming. She predicts that RSV will be significant in the future and is likely to peak in the winter of 2021/22.
In the case of influenza, the infectivity and evolutionary dynamics of circulating strains and the effectiveness of vaccines complicate the situation, but similar results can be achieved.
However, due to the low levels of infection, the influenza virus did not have many opportunities to mutate and evolve. This means that future strains are likely to resemble those that were circulating before the pandemic, so the vaccine remains effective.
According to Macquarie, the virus starts at a low baseline and may not have time to spread to large numbers of people during the seasonal window.
It is likely that it will take several years for the flu count to return to normal levels, Barr said.
Still, “we have to plan for a worse season,” Macquarie said. Even if the worst-case scenario never happens, available, widely used and effective vaccines can help prevent influenza outbreaks. This is especially important when the COVID-19 pandemic is not entirely behind us. “It’s very difficult to manage the two together,” he said.
