Tracking the virus and improving vaccines
Lesson summary
Hi there everyone, it’s Jeff and this is Plain English, where we help you upgrade your English with current events and trending topics. Today’s lesson is number 408 and that means JR, our trusty producer, has uploaded the full lesson to PlainEnglish.com/408.
In today’s lesson…It’s caused by a highly transmissible virus and that virus jumps from person to person via respiratory droplets released when we cough, sneeze, talk, and breathe out. Handwashing, hand sanitizer, social distancing, and mask-wearing can all slow the spread. Symptoms of the disease include fever, chills, sore throat, and, in severe cases, difficulty breathing. Most people recover in a few days, but it can be deadly, especially in the elderly and those who have compromised immune systems. Globally, tens of millions of people are infected every year; three to five million cases are severe, and between a quarter and a half-million people die annually.
Is this the scary future of COVID-19? Nope. It’s the everyday reality cause by influenza, that other highly contagious respiratory virus that you might have forgotten about. And on today’s lesson, we’ll talk about how the flu has been in hiding the last two years, and what that might mean for when it finally re-emerges.
The expression we’ll review today is “come to pass” and we have a quote of the week.
Scramble to protect against seasonal flu
Flu season traditionally lasts from October to April in the Northern Hemisphere, from April to October in the Southern Hemisphere, and year-round in the tropics. It spreads most commonly when the weather is cold and people are indoors; for that reason, it’s most intense in cooler climates.
Last fall, health experts in the Northern Hemisphere were bracing themselves for a “twindemic”: two concurrent pandemics of respiratory illnesses, COVID-19 and influenza. Fortunately, it didn’t come to pass . The influenza season around the world was extremely mild in 2020.
Experts believe that’s due to two factors. First, all the preventative measures that guard against the spread of COVID-19 also worked against influenza. With everyone cooped up at home, wearing masks in public, and keeping our distance, we inadvertently suppressed the spread of influenza. The other possible explanation is that people did get the flu, but they didn’t report it to their doctors, or their diagnosis was mistaken for COVID.
Misdiagnosis cannot fully explain the reduction in 2020 flu cases and experts agree that many, many fewer people suffered from the flu last year than in a typical year. That saved us from having to deal with dual pandemics. But it might also make the resurgence of the flu, when it does come, that much worse.
When we’re exposed to influenza, we develop antibodies that fight the virus. The antibodies are the strongest in people with the strongest immune systems, but regardless , they fade over time. In a typical flu season, people are exposed to low levels of the virus even if they don’t suffer symptoms. So, every fall and winter, people build up antibodies against the flu virus that help protect them against a stronger infection later.
That didn’t happen last year because we were all inside. So, when influenza starts spreading again, the general population will have less natural immunity built up than it would have had in a typical year.
There is another danger and that is related to vaccines. Influenza is caused by a family of viruses, and every member of that family looks and acts a little differently. In any given year , a handful of flu strains is in circulation. Vaccine makers, therefore, need to know what strains to build into their vaccines, but it’s impossible to know for sure which strains will circulate in the upcoming season. It is, however, possible to guess.
The World Health Organization, the WHO, does the guessing. They meet twice a year to study the existing global incidence of influenza and they recommend four strains to be included in the upcoming season’s vaccines. They base this recommendation on a program called the “Global Influenza Surveillance and Response System,” a network of scientific labs in 123 countries that test for influenza year-round. The WHO uses that data to study which strains are circulating in which places, and they make an educated guess about what will circulate in the upcoming six months.
The problem this year is that the World Health Organization doesn’t have a large sample size to study. In a typical year, about 17 percent of the samples collected by the global monitoring system are positive for influenza, and therefore provide important data to the WHO. Seventeen percent in a normal year. Last year, just 0.2 percent of collected samples were positive. With far fewer data available to analyze, the WHO has far less confidence in its educated guess than normal.
Flu vaccines are less effective than the COVID vaccines we’ve been hearing about, too. In a typical year, a flu vaccine is 70 percent effective against infection in the general population, but only about 50 percent effective in the elderly. In part, that’s because of the guesswork involved. Although, it’s also because of the long lead time necessary to make a flu vaccine.
Remember that the WHO meets twice a year to determine the vaccine makeup for the upcoming year. The meeting in February determines the vaccine makeup to be delivered in October in the Northern Hemisphere, while the meeting in September determines the makeup to be delivered in March to the Southern Hemisphere. The makeup of the vaccine is determined at least six months before the vaccine will be delivered. That’s because drugmakers must incubate the virus in chicken eggs, extract the virus, and then build and ship the vaccines. It takes a long time to make the vaccine this way. During that long wait, different influenza strains could spread, reducing the effectiveness of the vaccines before they’re even produced.
I want to leave you with a little bit of good influenza news before we finish. The development of mRNA vaccines against COVID-19 may be applicable to influenza vaccines too. Both Moderna and Pfizer, which made mRNA vaccines against COVID-19, have mRNA influenza vaccines in clinical trials. These can be produced much faster, ultimately reducing the time between identifying the strains and delivering the immunity to the public.
If COVID looks like it will become an endemic disease—meaning, that it’s always with us at a low level—then mRNA vaccines against both the flu and COVID-19 can be distributed at the same time. And there are new tests that can detect both diseases, improving their diagnosis.
Don’t forget influenza
I’m almost positive I had the flu this year. I got sick the day after I got back from Europe, and it was bad. I had fever, chills, cough, sore throat, headache, muscle aches, and it lasted more than a few days. I was convinced that I has caught COVID. But I went to get tested two days in a row, and both times the results were negative. By the time I saw a doctor, I was mostly better. They didn’t even bother to test for influenza.
But that just shows you how we’re all focused on the one thing that’s top of mind. I got tested twice for COVID, but it didn’t occur to me until days later that it might actually be influenza that I had. If so, it was an early case. That would have been late September. So of course, I got my flu vaccine after I got better! I guess I have double immunity now. Anyway, don’t forget your flu vaccine this year.
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