By D. W. G. Kalani Tharanga, JadeTimes News
Unpredictable Covid 19 Surges Continue to Challenge Public Health Efforts
Unlike other respiratory viruses that follow predictable seasonal patterns, Covid 19 exhibits an unpredictable behavior, with waves of infection occurring at any time of the year. For the past four years, epidemiologists at the US Centers for Disease Control and Prevention (CDC) have observed a notable spike in Covid 19 cases and hospitalizations every July, a phenomenon now referred to as the "summertime surge." This year, Covid 19 rates are particularly high in western states like Arizona, California, Hawaii, and Nevada, where the number of positive tests reached 15.6% by the week ending July 6th, a 1% increase from the previous week. Investigations by the CDC indicate that viral rates in wastewater are also on the rise, signaling a broader uptick in infections.
Across the Atlantic, the UK's Health Security Agency reports a similar trend, with positive Covid 19 tests rising from 4% at the end of March to 14% by the end of June. This surge has been attributed to the FLiRT subvariants, the latest evolution of the Omicron strain of Covid 19. These subvariants have adapted by mutating their spike proteins, essential for entering human cells and evading the immune system. According to Shan Lu Liu, director of the Viruses and Emerging Pathogens Program at The Ohio State University, these variants have struck a balance between escaping immune detection and binding to cells, driving the current increase in cases. Liu emphasizes the importance of booster shots, particularly for the elderly and immunosuppressed, to combat these new subvariants effectively.
The Challenge of Establishing Seasonal Patterns in Covid 19
The erratic behavior of Covid 19 contrasts sharply with other common respiratory infections, such as influenza and Respiratory Syncytial Virus (RSV), which typically surge in the autumn and winter months before subsiding in the spring and summer. Akiko Iwasaki, a professor of immunobiology at Yale University, suggests that the summer Covid 19 wave is partially exacerbated by factors like people gathering at festivals and concerts, and the heavy use of air conditioning, which dries the air and facilitates viral spread. In the UK, for instance, an increase in Covid 19 cases has been linked to people gathering in crowded venues to watch the Euro 2024 football tournament.
One key difference is that population immunity is much higher for other seasonal viruses due to their long standing presence, allowing them to infect primarily under ideal conditions during colder months. In contrast, Covid 19, still a relatively new virus, faces lower sterilizing immunity, meaning the body's ability to eliminate it before replication is weaker. This is exacerbated by low vaccination rates; as of July 7th, only 22.7% of adults in the US are up to date on their Covid 19 vaccines, compared to 48.2% for influenza. Denis Nash, an epidemiology professor at The City University of New York, notes that fluctuating population immunity due to inconsistent vaccination rates and previous infection waves contributes to the virus's unpredictable surges.
Looking ahead, experts like Andy Pekosz, a professor of molecular microbiology and immunology at Johns Hopkins University, believe that Covid 19 may eventually adopt a more seasonal pattern. However, Denis Nash cautions that this transition could take decades, given the longstanding nature of other respiratory viruses. For now, scientists agree that public health messaging must emphasize the importance of year round vaccination and access to antivirals to protect the most vulnerable populations, as Covid 19 continues to impact communities consistently throughout the year.
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