Lula with Covid: why it is possible to have the disease even after four doses of vaccine and previous infection

Former president Luiz Inácio Lula da Silva took to social media on Sunday night (5) to announce that he has Covid-19 again. His wife, Rosângela da Silva, Janja, also tested positive.

“Both are fine, former president [está] asymptomatic and Janja [tem] mild symptoms. [Eles] will be in isolation and medical follow-up in the coming days”, informs the post made on Twitter.

In the case of Lula, the fact that he received the fourth dose of the vaccine at the beginning of April stands out. The pre-candidate for the Presidency of the Workers’ Party (PT) was also diagnosed with Covid in the first year of the pandemic, in December 2020.

But, after all, how is it possible to have the disease for the second time, even with the immunization schedule up to date and a previous episode of coronavirus infection?

Scientific evidence points to at least three factors that help to answer this question: decline in immunity over time, emergence of new variants and high circulation of the virus.

What are vaccines for?

Immunologist Cristina Bonorino, a professor at the Federal University of Health Sciences in Porto Alegre, questions what it means to “get Covid” these days.

“What is getting Covid? Is it getting sick and going to the hospital? Having mild symptoms? Or simply testing positive? We need to understand that testing positive does not mean having Covid”, he differentiates.

“And vaccines do not prevent infection. As long as the virus circulates, people will become infected”, adds the specialist.

Regardless of the type of technology used, vaccines have one main goal: to get our immune system safely exposed to a virus or bacteria (or specific bits of it).

From this first contact, which will not harm health, our defense cells generate a response, capable of leaving the body prepared in case the real infectious agent decides to appear.

It turns out that this immune process is extremely complicated and involves a huge battalion of cells and antibodies. The immune response, therefore, can vary considerably depending on the type of virus, the capacity for mutations it has, the way in which the vaccine is developed, the person’s health conditions…

In the midst of all these processes, therefore, it is very difficult to develop an immunizer that is capable of preventing the infection itself, that is, blocking the entry of the cause of the disease into our cells.

But here comes a very important point: even in cases where the vaccine cannot prevent infection, often the immune response created from there can make the symptoms less severe in people who were immunized, thus preventing more severe diseases and deaths.

This occurs, for example, with vaccines against rotavirus and flu: whoever takes them can even become infected, but the risk of developing more serious forms of these diseases is considerably reduced.

And it is exactly this same phenomenon that we are seeing now with Covid-19: even if the available immunizations are not able to stop new waves of cases, they are working very well to prevent the worsening of most infections.

Proof of this are the most recent waves that occurred between the end of 2021 and the beginning of 2022, related to the spread of the omicron variant: although many countries have broken absolute records of cases, the rate of hospitalizations and deaths in these places was significantly lower in compared to previous moments of the pandemic.

A US Centers for Disease Control and Prevention (CDC) study published in March calculated the size of this protection. The data reveals that adults who have had three doses of Covid vaccine have a 94% lower risk of needing hospitalization, mechanical ventilation or dying, when compared to those who did not get immunized.

In short: Covid vaccines improve and modify some aspects of the immune system that do not block the entry of the virus into the body, but at least prevent it from replicating at a very high speed and causing damage that affects health in a worrying way.

And that’s good for the individual, who doesn’t develop these problems, and for the health system as a whole, which doesn’t get swamped with patients and can collapse.

Defenses That Fade

Now that you understand the main purpose of current vaccines against Covid-19, let’s explore a second question: in this context, why are booster doses necessary for some groups?

In Brazil, the Ministry of Health already recommends the application of a fourth dose of the immunizing agent for those over 50 years of age and for individuals with problems that affect the immune system.

Over the last few months, updating vaccination campaigns, with the adoption of extra doses, has proved necessary for a number of factors. The most important of them is related to the drop in immunity over the months.

Simply put, our frontline immune cells “forget” how to fight the coronavirus if they are not exposed to the pathogen after some time.

“This fall in antibodies is normal. We cannot have a high level of antibodies all the time”, explains Bonorino, who is also a member of the Brazilian Society of Immunology.

The application of booster doses, therefore, would serve as a kind of “reminder” to update our antivirus system. This strategy is even more important, from a public health point of view, when we consider people of specific ages (such as the elderly), or people with certain diseases, in which immunity usually doesn’t work that well.

In this sense, a study carried out by the Weizmann Institute of Science in Israel followed 1.2 million elderly people over 60 years old and observed that the frequency of severe cases of Covid was 3.5 times lower in the group of participants who had received the fourth treatment. dose, compared to those who only had up to the third dose of the vaccine.

This and other data only reinforce the notion that keeping the vaccination schedule up to date, according to what is recommended by health authorities, may not even prevent infection by the coronavirus, but it greatly reduces the risk of developing the complications of the disease — as seems to be the case of Lula, who does not show many symptoms, due to the little information available at the moment.

Walking metamorphosis

You can’t forget about the fact that the coronavirus is constantly changing. And the mutations that occur in his genetic code with each new replication open the way for the emergence of variants.

Some of these new strains, by the way, have caused considerable damage since the end of 2020: alpha, beta, gamma, delta and omicron carry important changes, especially in a part of the virus called the spike, which connects to receptors on the surface of our cells to give onset of infection.

In practical terms, significant changes in the genetic material of the virus make the work of the immune system even more difficult, which cannot very well identify the invading agent and launch an adequate response to contain it.

That is: even if the defense cells were able to mount a good counterattack against the original coronavirus (or one of the “older” variants, such as alpha or gamma), this may not be enough to stop the entry of the virus. micron in our body, as we speak of a modified version of the pathogen.

This is yet another factor that helps to explain why even people who were diagnosed with Covid-19 in the past — such as former President Lula himself — are at risk of catching the disease again a few months later.

“And the emergence of new variants will continue to happen as long as we have a part of the population that has not been properly vaccinated”, warns Bonorino.

And here you may be wondering: what about vaccines? Is it not time to update the immunizers so that they work even better against the variants that have emerged in recent times?

Several groups of scientists and drugmakers are researching this right now. But the results obtained so far are not encouraging enough to justify the launch of new products.

Despite losing some of their effectiveness, the vaccines available since the beginning of last year continue to work well enough for what they were created: to reduce the risk of developing the most serious forms of Covid-19.

high circulation

To complete, behavioral factors also have a role to play in this scenario in which reinfections become more common.

We live in a moment when public policies that tried to contain Covid cases – such as the use of masks in closed places and the prevention of agglomerations – were practically abandoned around the world. Without these barriers, the virus can circulate more easily.

The autumn and winter season in the Southern Hemisphere, when people tend to stay closer to each other and in places with little air circulation, also contributes to the increase in cases in the country.

In the specific situation of former President Lula, frequent participation in face-to-face events, such as rallies, debates and campaign meetings, also explains the reinfection: in a scenario of high viral circulation, it is practically unlikely that a person who is exposed so much on a daily basis to day do not have close contact with someone infected with the coronavirus.

This high viral circulation, by the way, can be observed in the Brazilian reality. According to information from the National Council of Health Secretaries (Conass), the country currently has a moving average of 29,000 new cases of Covid per day. Just over a month ago, at the end of April, this rate was at 12,000.

We can then summarize the whole situation with a relatively simple formula. Relative fall in antibodies + emergence of new variants + high circulation of the virus = increased risk of infection, even among vaccinated people or those who have had Covid in the past.

Fortunately, these individuals are better protected, as they still have an immunological memory good enough to prevent, in most cases, the complications of Covid, related to hospitalization, intubation and death.

To deal with this new wave and reduce the risk of problems both from an individual and collective point of view, experts make five main recommendations: be up to date with the vaccination schedule, wear masks indoors if possible, be aware of Covid symptoms. , take the test if you show any sign of infection and, if you really have the disease, stay in isolation.

You can read all the details on how to protect yourself from the increase in Covid cases in this report that BBC News Brasil recently published.