Globally, the cumulative number of confirmed COVID-19 cases has exceeded 20 million, and the death toll has exceeded 750,000.
In many countries and regions, people expect that the COVID-19 vaccine will be available as soon as possible so that people will be immune to the virus.
The protection time of different vaccines varies.
Some vaccines only need to be injected once and will work for a lifetime; while others can only provide short-term protection after injection. The flu vaccine we know well belongs to the latter.
In some extreme cases, the vaccine vaccinated in early autumn will fail before late winter.
Today, the top academic journal "Science" published an online paper explaining why many influenza vaccines are not long-lasting.
This research comes from the research group of Professor Rafi Ahmed of Emory University. As early as 1996, he assisted in the discovery of a type of B cell that stays in the bone marrow-bone marrow plasma cells (BMPC). After infection or vaccination, these cells continuously produce antibodies. In some cases, these cells will survive for several years to provide long-term protection. However, people do not know whether influenza vaccine can stimulate the production of these cells, nor whether these cells can protect against influenza for a long time.
To answer this question, the researchers designed an experiment that recruited 53 volunteers aged 20-45. In the experiment, these volunteers will provide scientists with bone marrow and blood samples for several weeks or months before and after the flu vaccine. From it, scientists can find plasma cells that only appeared after flu vaccine.
The study found that four weeks after the flu vaccine, bone marrow plasma cells specific to the flu virus were observed in the blood. However, after a year, these newly created cells disappeared. Correspondingly, although those newly produced antibodies start to increase one month after vaccination, they will start to decrease after one year. On the contrary, those antibodies that are not brought by the vaccine remain relatively stable during the year.
(Image by qimono from Pixabay)
Based on the results of these studies, the researchers understood the reason why the flu vaccine is not durable—only plasma cells that produce antibodies are not enough. If they cannot find a "settlement" place in the bone marrow, they will not last long by themselves. Of course, this discovery also allows us to find the direction of optimizing the vaccine. For example, no adjuvant to enhance the immune response is added to the current influenza vaccine. Researchers pointed out that if we add adjuvants to vaccines in the future, it is expected to extend the effectiveness of vaccines.
Considering that we do not know how long the COVID-19 vaccine will last, perhaps this study can give scientists a better understanding of the protective potential of the COVID-19 vaccine, so as to better respond to the global epidemic.