The issues are already starting to emerge.
When 85-year-old Colin Horseman was admitted to Doncaster Royal Infirmary in late December, he was suspected of having kidney disease. But shortly afterwards he contracted Covid-19 – at the time, about one in four hospitalized with the virus had been found there. He developed severe symptoms and was eventually put on a shower device. A few days later, he died.
At first glance, Horseman’s situation may seem pretty normal, though not as appealing to him. After all, at least 84,767 people have now contracted the disease in the UK alone at the time of writing. However, as his son recently explained in a local newspaper, less than three weeks earlier he had been among the first people in the world to receive the first dose of Covid- vaccine. 19 – the Pfizer-BioNTech version. He was due a second dose two days before his death.
In fact, most vaccines require increased doses to work.
Get the MMR vaccine – the measles, mumps and rubella – given to babies all over the world to prevent these deadly childhood diseases. About 40% of people who received just one dose are not immune to all three viruses, compared to 4% of those who received a second. People in the previous group are four times more likely to catch measles than the latter – and there have been uprisings in places where a high proportion of people have not stopped. on the full MMR vaccine schedule.
“The reason why people are so fond of boosters and consider them so critical is that they kind of put you into this other kind of tuning of your immune response, ”said Danny Altmann, professor of immunology at Imperial College London.
How booster vaccines work
When the immune system first meets a vaccine, it activates two important types of white blood cells. First are the B plasma cells, which are specifically targeted to produce antibodies. Unfortunately, this type of cell is short-lived, so even though your body may be swimming in antibodies within a few weeks, without a second sight this is often followed. with rapid decline.
Then there are the T cells, each of which is specifically designed to identify and kill a specific pathogen. Some of these, T memory cells, will be able to stay in the body for decades until they fall on their target – meaning that immunity from vaccines or diseases can last a lifetime. But crucially, you usually don’t have much of this type of cell until the second meeting.
Increasing the dose is a way for the body to reactivate the antigens – the molecules of pathogens that stimulate the immune system – to initiate part two of the response. “You’ve kicked all this interesting stuff,” Altmann said. “So once you are stimulated you will have a higher frequency of T and ditto memory cells to some extent for the size of the pool of B memory cells you have. They also make higher quality antibodies. .. “
On a second exposure to the same vaccine or pathogen, the remaining B cells are able to separate and form a threatening thrush of offspring, leading to a second spike in the amount of antibodies that are circulation.