When the coronavirus that causes Covid was discovered in early 2020, it was believed that it could be eradicated like its cousin SARS. Time has disproved this hypothesis: not only is it now thought to be a pathogen that came to stay, but its behavior is becoming increasingly similar to that of the rest of the coronaviruses that coexist with humans and cause the common cold. Most experts assume that it will be normal to become infected several times over the course of one’s life. “Unless it suffers mutations that change its behavior,” they always add.
The key lies in the response of the immune system. “What you see after vaccinations and natural infections is that most people produce a surge in antibodies that lasts a few months, three or four,” explains Marcos López Hoyos, president of the Spanish Society of Immunology. This protects them from being reinfected with the same variant during this period: reinfection with Covid is not impossible, but very unlikely. Then the antibodies decrease, although in most cases the body continues to avoid serious illnesses thanks to the T cells.
Over time after vaccination or infection (or both), the virus also mutates and eludes defense mechanisms (those that prevent infection), so a person exposed to the virus can be infected multiple times, as is the case with colds is the case. That doesn’t mean the virus is as serious as those that cause the common cold. At least not yet. The sixth wave caused more than 12,000 deaths in Spain, resembling a fairly virulent flu season.
The cases now appearing in Spain are of the Omicron variant but different from those that entered the country late last year. The BA.2 subline is clearly in the majority; there are also isolated others, such as BA.1, BA.3 and more rarely BA.4 and BA.5, according to reports from the Ministry of Health.
The problem with consistently monitoring these mutations is that in healthy people under the age of 60, diagnostic tests have not been indicated for almost two months. Therefore, much less is sequenced and it is very difficult to document reinfections. But they happen.
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It is even possible that a person who contracted omicron in the sixth wave is now infected with one of these sublineages. “It’s still a bit early, but it can happen because the variants change and escape acquired immunity, be it naturally or through the vaccine,” says López Hoyos. “We’re seeing a very good cellular response, so there’s no particular gravity. It is true that people die, but in most cases it is due to decompensation from previous illnesses,” he adds.
What could be seen as the seventh wave of coronavirus in Spain has stalled. Friday saw an incidence of 848.6 per 100,000 population in people over 60, the only ones being measured for the disease, practically the same as a week ago. And despite the fact that almost all protective measures against the virus have disappeared, the occupancy of intensive care units has not increased: in fact, fewer people are being admitted than before Easter, the moment when cases began to increase again. This reinforces the theory that the deepest defenses continue to protect the majority.
However, there is no good indicator of deaths in real time. It is a statistic that accumulates many delays and can only be measured reliably after a few weeks. If you look back you see that in Spain dozens of people continue to die from Covid every day. How is this possible when intensive care units are practically not increasing? Very frail people, usually very old people, are not usually accepted into these units as this would often involve therapeutic cruelty with very little chance of success. People with these characteristics and also very weak immune systems succumb to the virus.
For some older people, who were very protected during the first waves, this is often their first infection. But it is also not uncommon for them to get sick again after overcoming one of their first variants.
Waiting for new mutations
What will happen in the future will depend on the mutations the pathogen undergoes, according to José Jiménez, who researches coronaviruses and other emerging viruses at King’s College London’s Department of Infectious Diseases. “We see that the number of reinfections in the omicron variant is much higher than in the previous ones. On the other hand, it must also be taken into account that reinfection with other human coronaviruses that cause the common cold is common and the protection provided by vaccination or a previous infection decreases over time.
Javier Arranz, spokesman for infectious diseases of the Spanish Society of Family and Community Medicine (semFYC), agrees and believes that the evolution of this new disease will most likely follow the same paths: “We must assume that there are enough mutations to so the immunity can be bypassed and you can get infected again, although it’s usually mild.
To illustrate his vision of what could be to come, Vicente Martín of the Spanish Society of General Practitioners (Semergen) paraphrases a proverb used for motorcyclists who are said to be of two groups: those who have fallen and those who will fall. “With the coronavirus, there are those who have passed, those who will pass, and those who will do it multiple times in their lifetime, which will be very common.”