Early autumn is that magical time of the year when we wait for nature to turn the world around us golden and copper red. But it is also that period when specialists begin to direct our attention to the upcoming autumn-winter season of respiratory viral infections – mainly influenza, respiratory syncytial virus (RSV), and now also COVID-19.
Forecasting upcoming flu seasons has never been easy. First, because no two flu seasons are the same, and secondly, because the newly emerging SARS-CoV-2 “brought turmoil” not only to our world, but also to that of viruses and microorganisms in general.
This is what Prof. Dr. Radostina Alexandrova from the Institute of Experimental Morphology, Pathology and Anthropology with a Museum at the Bulgarian Academy of Sciences said in an interview about viral diseases in autumn and winter.
The U.S. Centers for Disease Control and Prevention (CDC) expects the coming season to be similar to last season in terms of total hospitalizations from COVID-19, RSV and influenza, the virologist explained.
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What have we learned from the flu season in the Southern Hemisphere?
Meanwhile, in the Southern Hemisphere, the flu season has just ended. While the same scenario may not necessarily repeat itself in the Northern Hemisphere, experts are always keeping a close eye on what is happening there in order to “predict” what lies ahead for the rest of the world.
We’ve learned that it’s possible for our flu season to start four to six weeks earlier than in pre-pandemic seasons, like last year. Therefore, it is not excluded that the peak of the flu will also occur earlier – at the end of December 2023 or the beginning of January 2024 (usually it is in January-February), said Prof. Alexandrova.
She recalled that on September 8, 2023, the US Center for Disease Control and Prevention (CDC) published the results of a study that looked at data on hospitalizations of children and adults related to respiratory diseases in almost 500 hospitals in five South American countries (Argentina, Brazil, Chile, Paraguay and Uruguay) during the 2023 winter influenza season (March to July 2023). It revealed that people vaccinated against this virus were half as likely (by 52%) to end up in hospital with the flu as those who were not vaccinated. This information is important because it confirms that the flu vaccine provides protection against serious consequences. Its effectiveness also depends on the match between the A viruses included in the composition and the circulating influenza strains.
Good news came from Australia and several other southern countries, which said there were no surprisingly dangerous or unexpected effects from the flu, the virologist said.
For whom is the flu vaccine especially recommended?
The US Centers for Disease Control and Prevention (CDC) recommends an annual flu shot for everyone six months of age or older, as long as certain symptoms or conditions are not present (for example, the extremely rare cases of severe, life-threatening allergies to specific vaccine ingredients— this restriction applies to all vaccines).
Influenza vaccines are especially important for people who are over 65 years of age, for children who are not yet two years old, for pregnant women or for women who have recently given birth.
When to get flu shots?
The advice from the US Centers for Disease Control and Prevention (CDC) is to get flu shots by the end of October (early in the season) before the flu starts to circulate widely.
It is necessary to provide time for the immune system to build up protection, which takes two to three weeks. However, the offer of the vaccine will continue after that, throughout the flu season. This is because its development may not be the same in different areas and because it is better to give the vaccine later than not at all, explained Prof. Radostina Alexandrova.
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What is happening with the spread of COVID-19?
After several months of very low levels of SARS-CoV-2 spread, the rise in cases of COVID-19 in the US and the Old Continent is already there. The rise began already in August, which was also reported by the European Center for Disease Control (ECDC) on August 17, 2023, Prof. Alexandrova said.
She explained that the return of people from leave and the entry of students into classrooms is helping this process. The new, more easily spread variants of the virus, as well as the fact that it has been quite some time since the last vaccine, contribute to this.
Due to the weaker circulation of the virus in recent months, our immune system has not had the opportunity to meet it and refresh its memory. According to experts, the probability that the level of hospitalizations will reach the values recorded at the peaks in the recent past is very small. The reasons for this are complex and include the baseline level of protection against severe infection that the vast majority of the population has acquired through vaccination and/or re-infection; the weakened “grip” of Omicron and its variants, which favor the upper parts of the respiratory system and cause a relatively milder clinical picture; our enhanced knowledge of the virus and the disease, and experience gained in treatment.
The virus keeps changing, and this should not surprise us, nor the fact that each successive variant that manages to establish itself and attract our attention escapes the immune response more successfully than the previous ones. At the moment, there is no data on a variant of SARS-CoV-2 with an increased severity of the clinical picture, said Prof. Alexandrova.
However, she noted that when talking about COVID-19, two things should not be forgotten. The first of these is that, however “harmless” SARS-CoV-2 may appear at first glance, it continues to be risky for the elderly and for people with co-morbidities, where it can cause severe and life-threatening illness. This is the reason why the updated monovalent vaccine against this virus – “updated” according to the currently circulating variants – is recommended in these groups of people.
The ongoing COVID-19 is still a serious challenge
Prof. Radostina Alexandrova emphasized that the long COVID19 continues to be a serious challenge. She noted that according to an April 17, 2023 publication in “Nature Reviews Microbiology,” it is a debilitating disease that occurs in at least 10 percent of SARS-CoV-2 infections. More than 200 symptoms affecting multiple organs and systems have been described. The affected inhabitants of the planet exceed 65 million. Factors such as female gender, severe initial illness, and comorbid conditions have been suggested to be associated with the risk of prolonged COVID-19. Between 2 and 4 million Americans have lost their jobs precisely because of this complication.
It is not yet fully clear to what extent the SARS-CoV-2 vaccine provides protection against prolonged COVID-19 and whether it can contribute to the recovery of patients if it has already occurred in them. The clarification of these questions is the subject of intensive work by scientists. An article in the journal “BMJ Medicine” from early 2023 analyzed data on 614,392 patients in five countries (US, UK, France, Italy and the Netherlands). The obtained results suggest that vaccines against SARS-CoV-2 may have a protective effect against the development of prolonged COVID-19, as well as help in the presence of one.
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Respiratory syncytial virus
This year, for the first time, we have two RSV vaccines approved for people 60 and older. One of them has the green light for use in pregnant women as well, with the idea being that the immunity built by the mother is transferred to the baby and protects it during the first six months of its life – the most critical period in terms of this infection.
Why is this important? More than 90 percent of children contract RSV in the first two years of life, and it usually starts like a cold and goes away in a week or two, the virologist explained. Prof. Aleksandrova specified that this is not the case with risk groups of children, which include children who were born prematurely; who have chronic lung or heart disease; with neuromuscular disorders, including difficulties in swallowing or clearing mucous secretions; with a weakened immune system. Children six months of age or younger are especially vulnerable. In them, the virus can affect the lower parts of the respiratory system and cause bronchiolitis (inflammation of the small airways in the lung) or pneumonia (lung infection).
According to the US Centers for Disease Control and Prevention (CDC), two to three out of every 100 babies infected with RSV may need to be hospitalized. The other vulnerable group of people are the elderly aged 65 and over, especially in the presence of lung and heart diseases, and in the case of problems with the immune system.
Can several vaccines be given at the same time?
This season, for the first time, we will have vaccines against all three viruses – influenza, SARS-CoV-2 and RSV. Influenza and COVID-19 vaccines can be given at the same time (in two different places), a practice that was used frequently during the last two flu seasons. And because the RSV vaccine is relatively new, we don’t yet have data on whether it can be given at the same time as other vaccines, the virologist explained.
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Professor Radostina Alexandrova is a Bulgarian biologist with professional interests in the fields of cell and molecular biology, virology, immunology, experimental oncology and oncopharmacology, tissue engineering (bone tissue modeling) and pathobiochemistry. In 1991, she graduated with honors in the specialty “Biochemistry and Microbiology” (today “Molecular Biology”) at the Faculty of Biology of the Sofia University (SU) “St. Kliment Ohridski”, with a specialization in “Virusology”. He is a doctor in “Virusology” and a professor in “Morphology”. He works at the Institute of Experimental Morphology, Pathology and Anthropology with a Museum at the Bulgarian Academy of Sciences (IEMPAM-BAS). She specializes in Slovakia, Hungary and Denmark. He is a member of the editorial boards of several Bulgarian and international scientific journals, the Union of Scientists in Bulgaria, the Bulgarian Anatomical Society.
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