Ottieni una migliore immunità contro il COVID-19 tramite la vaccinazione o l'infezione?

Quale protezione offre l'infezione precedente da COVID-19?

When you become infected with the virus that causes COVID-19, your immune system reacts in a number of ways. You may get symptoms of infection, which can vary depending on the particular strain. For example, a runny nose, mal di testa e affaticamento are common sintomi of Omicron.

Una risposta importante è la produzione di anticorpi. Gli anticorpi sono proteine che combattono le malattie nel corpo e svolgono un ruolo cruciale nel sistema immunitario. Gli anticorpi rilevano invasori infettivi come batteri e virus e aiutano il corpo a eliminarli, offrendo protezione contro future infezioni.

It is known that becoming infected with COVID-19 creates antibodies. Between April and August 2021, researchers behind the Studio ZOE COVID examined the antibodies of more than 8,000 people who had tested positive. Of those, 6,609 (80.67%) had a positive anti-N antibody test result - meaning they had some level of protective antibodies.

However, this also means one in five people did not and could therefore be at risk of catching COVID-19 again. Crucially, the risk of reinfection can depend on the strain of COVID-19.

La probabilità di reinfezione è più alta con Omicron

Data from the Ufficio Nazionale di Statistica show the risk of reinfection among people who caught an earlier strain of COVID-19 and were then exposed to the Omicron variant is 16 times higher than it was among people exposed to the Delta variant.

In December 2021, researchers at Instituto Nazionale delle Malattie Infettive del Sudafrica warned that Omicron has a substantial ability to evade immunity from a previous COVID-19 infection. This suggests the variant could lead to a wave of infections, even in populations with high levels of antibodies.

Le risposte immunitarie possono variare

While some people want to rely on having had COVID-19 previously as a form of protection, this is a very risky approach. This is because immune responses vary widely from person to person.

Although some people's immune systems create an effective immune response - so that they are unlikely to become infected again and thus can't pass the virus to someone else - others may not. Some people may be protected from becoming unwell with COVID-19 again, but can still become infected and can still transmit the disease to those around them.

Various factors can determine the level of COVID-19 immunity someone can get from infection, including underlying health conditions, some medicines and age. For example, gli anziani are less likely to have an effective immune response to infection.

"La maggior parte delle ricerche is showing that we are seeing multiple infections over time," says Rodney E. Rohde, a professor of clinical laboratory science and an infectious disease specialist at Texas State University. "This means that vaccini continue to offer the best and longest-lasting protection."

La protezione contro il COVID-19 diminuisce nel tempo

Even if someone does gain some immunity from past infection with COVID-19, this immunity lessens over time. According to one studio published in early 2021, people could have a level of infection immunity for at least five months, but they can still carry and transmit the virus.

This study was carried out when Delta was the dominant variant, so may not be relevant to subsequent strains such as Omicron.

Vaccinarsi offre alle persone la migliore possibilità di proteggersi e proteggere gli altri dall'infezione da COVID-19.

Although current vaccines are less effective against infection with Omicron than previous variants, studi show that vaccination does provide a high level of protection against severe disease and hospitalisation. Getting a richiamo jab is the most effective way to protect yourself from both infection and severe illness from Omicron, ricerche shows.

"I vaccini contro il COVID-19 sono raccomandati, anche se hai già avuto il COVID-19," dice Rodhe. "I dati di ricerca di Johns Hopkins Medicine e dei Centers for Disease Control and Prevention (CDC) degli Stati Uniti indicano che un vaccino contro il COVID-19 offre anticorpi più duraturi e altra immunità che proteggono dal contrarre il COVID-19, sia che si sia stati infettati dal SARS-CoV-2 o meno."

Il Studio ZOE COVID suggests that protection via natural immunity is less effective overall than vaccinazione.

It's not yet known how long immunity to COVID-19 from vaccines will last. Therefore, it's possible that we may need vaccini di richiamo annuali to protect against future variants, particularly for vulnerable or immunocompromised people.

Precedente infezione da COVID-19 e vaccinazione potrebbero offrire una buona protezione

There is a growing body of research that suggests infection plus vaccination provides the best protection against catching COVID-19. This combined protection may last longer than vaccination alone, according to a 2021 study published in the journal Science, anche se non è stato dimostrato.

Ultimately, the only way to get naturally acquired immunity is through infection with COVID-19, which is risky. When you become infected, you can infect other people - including those who are vulnerable - and you can spread the disease. There is no way of knowing just how unwell you may become and those who are unvaccinated are at greater risk of severe illness. And even if you avoid hospital, you are at risk of potentially highly debilitating long COVID, attualmente ritenuto influenzare 1.3 million people (2% of the population) in the UK.

However, vaccination allows you to build up your immunity safely, without risking your health and the health of those around you. There have been rare reports of serious side effects seen - such as the rischio di coagulo sanguigno raro, cerebral venous sinus thrombosis (CVST). But the risk of this complication is about 2 in a million from vaccination: the risk of the same clot from catching COVID-19 is 8-10 times higher.

Similarly, while there has been much concern in the media about the risk of myocarditis (inflammation of the heart muscle), in absolute terms the risks are extremely small. A review of 8.7 million COVID-19 vaccines given to children aged 5-11 in the USA showed 11 casi confermati di miocardite (1 in 800,000), who recovered after a 'mild clinical course'. By contrast, among 12 to 17-year-olds infected with COVID-19, the l'incidenza di miocardite era just under 1 in 2,200.

Not only do vaccines lower your chance of developing COVID-19, they also reduce how unwell you become if infected. Your COVID-19 immunity can be easily enhanced and prolonged by getting richiami over time.