Some of the variants detected increase the possibility that vaccinated people, despite being protected, infect others.

Covid-19 vaccine.  EFE / EPA / SERGEI ILNITSKY

Does vaccination completely prevent infections? The short answer is no. You can still get infected after you get your vaccine. But your chances of becoming seriously ill are slim to none.

Many people think that vaccines work as a shield, preventing a virus from infecting cells completely. But in most cases, a person who gets vaccinated is protected against disease, but not necessarily against infection.

Each person’s immune system is a little different, so when we say that a vaccine has a 95% effectiveness that just means that 95% of people who have been vaccinated will not get sick.

These people could be completely protected from infection, or they could be infected but remain asymptomatic because their system clears the virus very quickly. The The remaining 5% can become infected and sick, but it is highly unlikely that such people will be hospitalized.

Vaccination does not prevent infections 100%, but in all cases it gives the immune system a great advantage against the coronavirus. Either complete protection against infection or, if you develop any level of disease, you will always be better after receiving your dose of vaccine than if you had not received it.

Does infection always imply transmission?

Transmission occurs when enough virus particles from an infected person enter the body of another uninfected person. In theory, anyone infected could transmit the virus. But vaccination will reduce the chance of this happening..

In general, although vaccination does not completely prevent infection, will significantly reduce the amount of virus that comes out of the nose and mouth and it will shorten the time the virus is shed.

This appears to be the case for coronavirus vaccines. In a recent previous study which has not yet been peer-reviewed, Israeli researchers screened 2,897 vaccinated people for signs of infection. Most had no detectable virus, but people who were infected had a quarter of the amount of virus in their bodies than unvaccinated people those who were tested at similar times after infection.

Fewer coronavirus viruses means less chance of spreading it, and if the amount of virus in your body is low enough, the probability of transmitting it can be almost zero.

However, researchers do not yet know where that cutoff is for the coronavirus, and since vaccines do not provide 100% protection against infection, experts recommend that people continue to wear masks and maintain social distancing measures even after being vaccinated.

What about the variants?

Have surged new variants of coronavirus in recent months, and recent studies show that vaccines are less effective against some, such as variant B1351 first identified in South Africa.

Every time SARS-CoV-2 replicates it gets new mutations. In recent months, researchers have found new variants that are more infective, which means that a person needs to breathe in less virus to become infected, and other variants that are more transmissible, which means that they increase the amount of virus that a person gives off. And researchers have also found at least one new variant that seems to have an easier time evading the immune system, according to the first data.

For the South African variant, vaccines still provide more than 85% protection against a serious illness of covid-19. But when mild and moderate cases are counted, vaccines provide, at best, only about 50% -60% protection. That means at least 40% of vaccinated people will still have a strong enough infection and enough virus in their body to suffer from at least moderate illness.

If vaccinated people have more viruses in their bodies and it takes less virus to infect another person, there will be a higher chance that a vaccinated person can transmit these new strains of the coronavirus.

If everything goes fine, vaccines will very soon reduce the rate of serious illness and death worldwide. Undoubtedly, a vaccine that reduces the severity of the disease also, at the population level, will reduce the amount of virus that is transmitted.

But Due to the emergence of new variants, vaccinated people still have the potential to spread and transmit the coronavirus to other people, whether they are vaccinated or not. This means that vaccines are likely take longer to reduce transmission and in favoring herd immunity than if these new variants had never emerged.

The The length of time this process will last will be the result of the balance between the efficacy of vaccines against emerging strains and those that are communicable and infectious. let them be the new strains.

* Deborah Fuller is Professor of Microbiology at the University of Washington, USA.

** This article originally appeared on The Conversation.