Covid: 3 certainties and 3 doubts about the future of vaccines, according to a Brazilian scientist from Oxford

In the United States alone through November 2021, vaccination against Covid-19 saved 1.1 million lives, prevented 10 million hospitalizations and prevented 35 million coronavirus infections.

It was with this data, recently released by the Commonwealth Fund, that Brazilian physician Sue Ann Costa Clemens began her presentation via videoconference during the Brazilian Congress of Infectious Diseases, held between December 14 and 17 in Goiânia.

The expert analyzed, for about an hour, the progress made in recent months with vaccines against Covid-19 and what are the future prospects in this area.

“In just a few months, we were able to train professionals, create an entire infrastructure, accelerate the transfer of technologies and improve the regulatory paths for new products. May we be able to maintain these lessons for years to come,” he said.

Director and one of the founders of the Master’s Program in Vaccinology at the University of Siena, Italy, Clemens is also a professor of Global Health at the University of Oxford, United Kingdom, and works in the Clinical and International Relations Department of the Carlos Chagas Institute, in Rio de Janeiro.

The doctor is also a senior vaccine development adviser at the Bill and Melinda Gates Foundation and was directly involved in the creation of immunizers against rotavirus and HPV.

During the current pandemic, she serves as director of the Oxford-Brazil Vaccine Group and was one of the coordinators of the clinical trials that proved the efficacy and safety of the AstraZeneca/Oxford University vaccine. Part of these studies were even carried out in our country.

According to the expert’s analysis during the event, vaccination against Covid brought a series of lessons and legacies, such as the creation of clinical research centers in various parts of the world and knowledge about the combination of different technologies, but many challenges remain. ahead — such as the need to expand the production of doses and protect the entire world population.

How did we get here?

Clemens began his talk recalling two recent global health crises: the H1N1 pandemic in 2009, and the Ebola epidemic, which affected some African countries since 2014.

“In these two cases, efforts were made to create vaccines, but the products arrived a little late or faced problems in the production and regulation phase”, he analyzed.

“But when we think particularly about Ebola in 2014, we see that this episode helped to make the world aware of the need to invest in technology and innovation to prevent epidemics and pandemics,” he said.

As an example of this greater health concern, the doctor mentioned two global actions that have taken place in recent years. First, the publication of the WHO (World Health Organization) list of priority diseases as of 2015.

This document, updated from time to time, has allowed a greater focus on the most worrisome infectious agents, for which prevention and treatment methods must be researched.

The second fundamental step was the creation in 2017 of the Center for Preparedness and Innovations for Epidemics (Cepi, its acronym in English).

“From then on, we had a greater awareness from governments and institutions that we needed to accelerate the development of vaccines for pathogens with epidemic potential”, explained the expert.

Clemens also recalled that one of the biggest barriers when it comes to researching new immunization agents is the difficulty in carrying out larger clinical trials, which involve up to tens of thousands of volunteers, the investment of millions of dollars and an enormous infrastructure.

To respond to the Covid-19 pandemic and develop solutions in record time, it was necessary to tackle this problem.

“Some institutions started to fund the organization of research centers in various parts of the world. In four months, we were able to train and establish 22 sites for clinical trials in seven countries in Latin America,” he said.

“And it was these centers that helped the world to validate vaccines and start producing the doses that have been used in recent months,” added Clemens.

The doctor highlighted that, in the case of AstraZeneca’s vaccine, the negotiation process to bring clinical research to Brazil began in April 2020. The tests began in mid-July of that year and, in November, the efficacy and safety of the product was proven.

“In about eight months, we were able to validate an immunizing agent that would become one of the largest suppliers of the Covax Facility [instrumento internacional de compra e distribuição de doses para os países mais pobres]”, he said.

the three certainties

Launching and sustaining a worldwide vaccination campaign against a new disease that kills thousands every day was an immense challenge.

And Clemens points out that this entire process, which is still ongoing, brought a series of lessons learned and required adaptations along the way.

The first fact that the doctor mentioned was the increase in the time interval between the two doses and heterologous regimens (in which an individual takes AstraZeneca and then Pfizer, for example).

“When we develop vaccines, it is not enough to prove their efficacy. We need to monitor the persistence of antibodies, the effectiveness of the doses and, eventually, make adaptations to the campaign,” he said.

“Increasing the interval between the first and second doses, for example, was very important, as we were able to vaccinate more people in times of scarcity.”

Brazil itself used this strategy in the turn from the first to the second half of this year: the two doses of Pfizer or AstraZeneca were applied almost three months apart. In this way, it was possible to quickly protect, even if partially, a large portion of the adult population.

A second aspect that has become a certainty in recent months is the need for booster shots.

The first recipients of a third vaccine were the elderly and individuals with compromised immune systems, but the arrival of new variants (the case of delta and micron) accelerated the need to guarantee extra protection for practically all groups.

“The effectiveness of the two doses of vaccine against omicron is lower, it is around 40%. A third dose increases this rate to 70% or 80%. So, if there is a possibility of giving the booster, it is better to be done,” analyzed Clemens.

Currently, in Brazil, the third dose is guaranteed to all people over 18 years of age. According to the latest Ministry of Health announcements, this booster should be given four months after complete primary immunization (with two doses, in the case of those who took CoronaVac, Pfizer and AstraZeneca, or with one dose, in the case of those who received Janssen ).

The last certainty on the list has to do with the inequality in the distribution of vaccines across the planet.

“These days I was doing interviews for a project with candidates who are from Eritrea, Africa, and they told me that vaccination against Covid-19 practically did not start there,” he said.

“As long as we don’t vaccinate everyone, we will continue as a storehouse of new variants. This is exactly what we have just seen with the emergence of omicrons”, warned the researcher.

the three doubts

As much as science has found many answers in record time to deal with the pandemic, there are some important questions about the future of Covid-19 vaccination.

In the view of the Brazilian scientist, the first and second questions on this list are related to the protection period of vaccines and whether it will be necessary to carry out annual immunization campaigns, like what happens with the flu.

“We still need to understand the dynamics of the variants, whether any of them will become the dominant one and how this scenario will change from now on,” he said.

“It is possible that we have an annual vaccination for some age groups, but not for all. It remains to be seen whether we will need to adapt the doses and how long it would take,” he added.

And all these uncertainties are the result of not enough time to measure how long immunity lasts after vaccination, or how defense cells and antibodies interact to protect us from coronavirus infection (or its more severe forms) after months or years old.

“We are studying each vaccine platform, how long the protection lasts, what is the persistence of antibodies over time…”, listed Clemens.

In conclusion, the last question may even represent hope: will it be possible to use only half a dose of vaccine as a booster?

Clemens explained that studies in this area are ongoing. If the responses are positive, this could be some of the best news in the coming months.

“With half a dose, we can vaccinate a larger number of people much faster”, projected the doctor.

“This would expand our capacity at a time when there is a shortage of infrastructure, material and labor,” he amended.

“We are running behind to increase production and vaccinate the world, especially Africa, much faster,” he concluded.