The new flu variant is more contagious and resistant to vaccines

The end of autumn and the beginning of winter in Málaga is proving more challenging than other years due to the early start of the flu season within a timeframe of between four and seven weeks, as already reported by SUR. However, the concern of regional and national authorities does not lie in this acceleration of the arrival of seasonal flu, nor in the growth already detected last week in hospital emergencies and primary care centers from this virus and others such as those causing bronchiolitis, Covid-19, or colds, but in the arrival of a new flu mutation, a variant of the H3N2 virus (flu) known as subclade K, which has greater transmission capacity and vaccine resistance.

The Spanish Society of Family and Community Medicine (semFYC) alerted last week about the atypical behavior of the current respiratory virus season, with an advancement of one month in the start of flu activity due to a new variant of the virus that has been circulating since April or May in the European Union: "It is a more transmissible virus, although it does not imply greater severity." The main risk falls on vulnerable people: the elderly, immunocompromised, or patients with chronic diseases. Although the virus is not more virulent, "it can cause more admissions and complications, because it affects people who were protected by the vaccine and are not at the level of other years when there have been fewer antigenic changes."

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The epidemiological advance anticipates an increase in cases earlier than usual and shortens the window for effective vaccination, important for risk protection. If it is confirmed that subclade K is the predominant one, the alterations of the hemagglutinin protein, key for the virus's attachment to human cells, must be considered, which may hinder its recognition by the immune system, both after vaccination and after a previous infection, explaining the advance of circulation and the increase in infections even in vaccinated individuals.

Increase

If there was already a spike in flu cases last week, it is now evident that the increase is accelerating in emergencies, confirm hospital sources. This virus could be behind the fact that flu cases were treated in hospitals during last summer, creating peak assistance (in combination with Covid-19) in Málaga.

That in Málaga the flu season and other acute respiratory infections (including flu, Covid-19, bronchitis, and bronchiolitis) have arrived earlier than usual is clear: the rate per 100,000 inhabitants is 211.1 in the week of November 17 to 23, 57% more than in the week from October 13 to 19, according to the Weekly Surveillance Report of Acute Respiratory Infection from the Andalusian Government.

"Rapid expansion"

Ana María Ortega Prieto is the co-researcher responsible for the Immune Response to Viral Infections Group at the Biomedical Research Institute of Málaga (IBIMA Plataforma BIONAND). "The K subclade of the H3N2 virus is a genetic variant of the influenza A virus that presents changes in the protein the virus uses to bind to our cells. These changes make our immune system recognize the virus poorly, because it is a virus that looks less like the H3N2 that have circulated in previous seasons," explains Dr. Ortega Prieto, adding that "it is spreading rapidly and already accounts for a third of all flu viruses analyzed between May and November this year worldwide and almost half of those analyzed in Europe: these data suggest that the virus could be transmitted more easily."

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However, there is no increased potential severity, in principle. "What can happen is that, as more people get infected than in other years, the number of complications may also increase simply because there are more vulnerable people exposed to the virus," she notes, to highlight that "it is slightly different from the viruses used in this season's vaccines, which can cause a decrease in their effectiveness, especially when it comes to preventing infections. However, although current data on its efficacy are quite limited, preliminary results published in England indicate that the vaccines continue to offer good protection against the most severe cases."

The main consequence of this flu variant could be "a higher number of cases than in previous years and in a shorter period of time: this may mean greater healthcare pressure, especially if it coincides with other respiratory viruses. For older people or those with chronic diseases, the risk of complications is greater," emphasizes Dr. Ortega Prieto to SUR.

Combating the new mutation

To combat it, the ideal is "to vaccinate vulnerable groups as soon as possible, start antiviral treatment early in people infected with a higher risk of severe illness, and consider the use of antivirals as prophylaxis when outbreaks are detected in sensitive settings such as nursing homes. Additionally, it is important to continue maintaining good epidemiological surveillance."

Essential strategies to curb the flu: hand washing, ventilation, and special attention to the vaccine

As prevention measures, she proposes "to ventilate enclosed spaces well, wash hands frequently, avoid contact with vulnerable people if they show symptoms compatible with the flu, and above all, get vaccinated as soon as possible."

Plan of the Andalusian Government

The Andalusian Government has activated its own action plan against the flu, after the Health, Presidency, and Emergencies Minister, Antonio Sanz, announced last Friday that the latest data "reflects that the positivity for the flu virus has increased compared to the last two weeks, reaching 21.6%." The minister also reported that the flu season has advanced between 4 and 7 weeks, with the H3N2 virus being responsible. The Government, in a press release, stated: "A virus that has not been the dominant virus in recent seasons, which could lead to a decrease in immunity in the person."

Among other measures, since last Monday, the use of masks is recommended for staff and users of public and private health and social care facilities (nursing homes, centers for people with disabilities), and they are asked to consider the mandatory use of masks in their consistency plans.