It’s always virus season now

By David Quammen

NEW YORK: Health officials would like to remind you that we are entering that time of the year still quaintly known as flu season. That means autumn to spring. Kids go to school, adults spend more time gathered indoors, people breathe and speak and sneeze and cough at one another, and the latest influenza virus spreads widely.

The reason flu season seems a quaint idea is that we now hear about and maybe worry about so many viruses all year. And well we should.

What if there’s a simultaneous surge of Covid and seasonal flu this autumn? What if infections of respiratory syncytial virus, known as R.S.V., peak at unusual levels, as they did in the 2022-23 season? What if the new strain of mpox, which is especially virulent, continues spreading in Africa and beyond? What if this year’s flu combines with the dreaded H5N1 bird flu and emerges as a nightmare flu? What if a novel virus destined to be called SARS-CoV-3 emerges from a horseshoe bat in a rural village somewhere, gains a few key mutations and comes barreling through the world’s airports?

Oy vey and déjà vu. It’s always virus season now. Maybe none of those worst-case scenarios will happen, but to assume so is to count on fool’s luck.

The notion of flu season is a relic of times when one virus could transfix our response efforts and dominate our collective consciousness. Influenza in 1918. H.I.V. in 1980s and ’90s. Ebola in 2014. We can no longer afford to react on a case-by-case basis. Today we need a broader vision. We need personal, governmental and technological responses that address the full spectrum of viruses that disrupt our lives.

Because they will continue to disrupt our lives. We live amid viruses. We eat them. We breathe them. We touch them on doorknobs and cafeteria trays. All the wild and domestic animals with which we interact, from mosquitoes to mice to the sparrows on the bird feeder and the monkeys in the temple gardens, carry their own freights of them in wondrous variety. Most of these viruses have no chance of infecting a human, but many do. The best way to protect yourself and your family is just what health agencies recommend: Get the vaccines if reputable ones exist.

The best way to help protect your community, your country and the rest of humanity is a more complex proposition. The answers range from public health measures such as better virus surveillance to ending our bone-headed science denialism and finally supporting pandemic preparedness. But it’s not my purpose to unpack those big topics in this small spurt of words.

My purpose is more modest: to refresh your awareness of something you can’t see, not without the help of an electron microscope. Even the human genome contains a sizable portion — roughly 8 percent of it — that was once the genomes of ancient retroviruses, acquired and internalized by our ancestors in the course of infections.

Viruses of concern to humans come and go on various schedules. American dairy cows began their flu season this year around March 25, when the first infections with bird flu were reported in herds in Kansas and Texas. Measles outbreaks tend to be seasonal but more complex. In the tropics they may peak in the dry season, while in temperate climates measles correlates more with school schedules. And now that warmer temperatures are welcoming tropical mosquitoes farther north and south — including ones that transmit viral diseases like yellow fever and dengue — people in Florida and Italy may find that their worst virus season is summer. Climate change is the new force applied to the viral calendar.

Each year another seasonal vaccine is offered because influenza viruses evolve and mix continuously; their genomes entangle like shape-shifting snakes. The most concerning threat is different each year. This year’s flu vaccine in the United States is what’s called trivalent, or three-powered, meaning it contains elements from three different influenza viruses, all of which are circulating and any of which may prove most pervasive and problematic. Manufacturing flu vaccines takes months, so calculated decisions, mixing science and foresight, must be made long before autumn. Increasing efforts to produce even more kinds of vaccines, including some that target multiple virus strains, signal scientific awareness of the point I’m trying to make: We know a virus might get us, tomorrow or next season, but we can’t say which.

Hence the need for a universal flu vaccine, such as one that’s now in clinical trials at the National Institutes of Health. Hence the need for a universal coronavirus vaccine, toward which scientists at the California Institute of Technology, among other places, are working. Hence the need to create combination vaccines that protect against Covid-19 and influenza in one shot, which are also under development in the United States, China and elsewhere. Hence the need to improve ventilation systems for public and private buildings, which can significantly reduce the spread of respiratory viruses.

These are urgent challenges, at which laboratories and public health authorities all over the world are laboring busily. Science takes time; applying its findings takes patience. Persuading the public to adopt behavioral changes — some of which involve a prick in the arm, some of which require placing community welfare on a level with individual independence — is a task that may seem almost Sisyphean, but it remains crucial and doable.

Flu season in America is no illusory concept, and I don’t mean to deride it, merely to expand it. Get the jab if you’re not disqualified by special health conditions. Don’t disqualify yourself by indifference or groundless suspicions. But bear in mind that virus season doesn’t end with the first swallows of spring. We’re in it for the duration.