If vaccinated people, especially the elderly, are becoming infected and, in some cases, dying, it is not the fault of the vaccines. They are great and are the big stars in the fight against the pandemic. The virus continues to circulate and new variants are emerging and this is due to the total lack of effective combat against the pandemic by those who should lead the nation. Vaccines fight against the virus, against misinformation, against ffake news, against those who are worried about re-election, vaccines fight against the lack of enlightenment campaigns in society, against the countless and constant attacks by denialist politicians on science, on vaccines themselves, on non-pharmacological measures, such as the use of masks, distancing physical and measures of lockdown and movement restrictions.
Since the beginning of the pandemic, we have been observing a huge disconnect and lack of political will to combat the disease, the many political issues contaminating the debate in the area of public health, the delay in purchasing vaccines and slow vaccination due to the lack of vaccines. Other factors responsible for the fact that the virus is infecting older vaccinated people is the irresponsibility of some politicians, journalists and pseudoscientists and doctors in defending treatments with early kits containing ineffective drugs, the lack of empathy on the part of a large part of the population that does not cooperate, little testing and ineffective contact tracing.
We cannot let these rare episodes of vaccinated people dying generate waves of misinformation and false narratives that "there is no point in taking the vaccine". If we take away the vaccines, what are we going to put in their place? And we are observing around the world that the people most affected by the Delta variant of the virus (originally detected in India) are unvaccinated people. There is a pandemic among the unvaccinated.
Vaccines are overcoming all this scientific denialism and ignorance and are saving millions of lives around the world. Even in this scenario of an increase in cases due to the Delta variant, the number of hospitalizations, serious cases and deaths are proportionally much lower, thanks to vaccines! We need to remember that the presence of comorbidities and immunosenescence – a natural aging process in the body of elderly people – contribute to a decrease in the capacity of the vaccine response for immunological protection. Older people produce fewer antibodies, which are also less potent than those of younger people. Therefore, any “carelessness” must be avoided in order to spread the virus to the elderly, even if they have been vaccinated. The strategy to combat the pandemic is mass vaccination, broad vaccination coverage and dialogue with society. Vaccines are the best tool, but other health control measures are essential to offer other layers of protection, such as non-pharmacological measures to increase collective protection.
How long will the pandemic last?
I don't know, no one knows, but I know that without effective combat measures organized by the Ministry of Health, we won't get rid of it anytime soon. We have been immersed in this unprecedented health and political crisis for around 18 months. We lost around 570 thousand Brazilians (very underreported), we are all tired, children out of school, a huge crisis with around 15 million people unemployed, people going hungry and with around 35 million Brazilians living in the most absolute informality .
The number of infected cases and deaths is still high, the Delta variant circulating, slow vaccination and campaigns to defame vaccines, especially petty political issues to question a particular vaccine, when they are all contributing to saving lives, make the scenario more complicated. If the population does not understand that vaccines are saving lives, that they are our best strategy to get out of the pandemic, it will be difficult.
Vaccines alone will not do magic, we need several actors working in the same direction: vaccines, non-pharmacological measures and epidemiological control and genomic surveillance measures. There will be little point in vaccinating and suspending or making the use of masks and physical distancing more flexible. The virus will continue to circulate, infecting unvaccinated people, who will unfortunately spread the virus to vaccinated people, especially the elderly, who have a more compromised immune system and whose protective response provided by vaccines is less efficient.
We know that older and immunosuppressed people have a more compromised immune system, which does not provide as robust protection, even when vaccinated. These groups produce fewer antibodies, which are also less potent. All vaccines in use against Covid-19 reduce serious cases, hospitalizations and deaths, but do not eliminate the possibility of infection, as no vaccine guarantees 100% immunity against Covid-19.
We are observing around the world that the people most affected by the Delta variant of the virus are unvaccinated people, there is a pandemic among the unvaccinated. This happens due to people's relaxation, who, because the vaccines are working so well and reducing hospitalizations and deaths, think that the pandemic is under control. The denialism of politicians who attack vaccines, the use of masks, physical distancing, science and discourage part of the population from getting vaccinated also contributes.
Vaccination needs to be accelerated quickly
Vaccination in Brazil remains slow e suffering from delays in dose deliveries. In the scenario with the Delta variant, it is necessary to greatly accelerate the application of the first dose, review the interval for application of the second dose of the AstraZeneca and Pfizer vaccines, following the instructions in the leaflets and guarantee the homogeneity of vaccination in the various states and municipalities . At the moment, Butantan's CoronaVac vaccine has the shortest application interval (28 days between doses), when compared to the AstraZeneca and Pfizer vaccines (~90 days between doses).
Data from 15/08/2021 shows that 164.489.479 million doses were applied in Brazil, with 114.867.227 million people (54,25% of the Brazilian population) took the first dose and 49.622.252 million of people (23,43% of the population) took the second dose or the single dose of the Janssen vaccine. These numbers refer to vaccination over a period of approximately 7 months, since 17/01/2021, with the application of the first dose of CoronaVac to nurse Mônica Calazans, who works in the ICU of the Emílio Ribas Institute of Infectious Diseases, in São Paulo.
This is the number of people over 18 years of age who took either the single-dose vaccine from Janssen or the two-dose vaccines from CoronaVac, produced in Brazil by the Butantan Institute, the AstraZeneca vaccine (Covishield), produced at Fiocruz and the Pfizer vaccine. It is essential that people who took the first dose return within the deadline for the second dose. And it is absolutely essential that people who have not taken any dose of vaccines understand that this decision puts the lives of everyone around them at risk and harms the fight against Covid-19.
As non-pharmacological measures must be maintained even vaccinated
But vaccines alone, no matter how good they are, will not get us out of this health crisis. Vaccines are fantastic and we need them as they offer the most important layer of protection against Covid-19. However, to be truly effective in reducing the circulation, spread and blocking the transmission of new variants of the virus, vaccines need support from the population in terms of maintaining non-pharmacological measures, such as the use of masks, especially N95 or PFF2, the physical distancing, hand hygiene habits, avoiding crowds in closed places with poor ventilation.
In addition to these measures, which together are fundamental in combating the pandemic, it is also essential to carry out epidemiological control measures such as testing, isolation of infected people, contact tracing and genomic surveillance, monitoring the appearance of variants of concern. I don't understand why there is no national mask delivery strategy N95 or PFF2 for the most vulnerable and susceptible population in this country. How many masks and how many doses of vaccines could be obtained with the money allocated to the electoral fund?
CLARIFICATIONS ABOUT DOSES AND VACCINE SCHEDULE
PWhy do people not come back for the second dose?
Without a doubt, one of the causes is the lack of national campaigns to inform the population about the importance of high vaccination coverage, regardless of the vaccines. People should not choose vaccines, but they are not being adequately guided. There is also a lack of vaccines, unfortunately. Other important factors are doubts about the intervals between doses, which were extended to 3 months, in the case of the AstraZeneca and Pfizer vaccines due to a lack of vaccines. The population's fear of possible adverse effects from the first dose and the fear of more serious effects from the second dose also contribute.
The denialists from the hate office and anti-vaccines, pseudojournalists, pseudoscientists and some obscurantist doctors who don't understand anything about science take advantage. We need to defend all vaccines, combat this political opportunism, the politicization of science and the anti-vaccine movement, which is discrediting vaccines and defending their denialist ideological narratives. It is essential to apply the second dose to prolong, strengthen and intensify the effect of the first dose of all vaccines, with the exception of the Janssen vaccine, in a single dose.
As we do not have national campaigns to educate society in all media, part of the population is insecure, suspicious of vaccines and afraid of adverse events. The population needs to understand that the virus causes very serious adverse effects, kills and leaves irreversible consequences. To the fake news against vaccines reach the population with enormous capillarity.
Complying with the vaccination schedule is essential for those who take it in two doses
The first dose of any of the vaccines offers only partial immunity against the Delta variant, making it necessary to complete the vaccination schedule. Results of a study scientific published on 12/08/2021 in the magazine The New England Journal of Medicine, involving around 150 thousand people, show that the Delta variant causes the effectiveness of the first dose to decrease from approximately 50% to 36% in the case of the Pfizer vaccine and to 30% in the case of the AstraZeneca vaccine, when compared with the results obtained with the Alfa variant, which appeared in the United Kingdom. After applying the second dose, the vaccines maintain efficacy data close to those of the originals, with a small drop, compared to the data obtained for the Alpha variant. In the Delta variant scenario, the Pfizer vaccine had a drop from 93,7% to 88%, while the AstraZeneca vaccine showed a reduction from 74,5% to 67%, after two doses.
The second dose of Pfizer is recommended instead of AstraZeneca
On 14/08/2021, the Ministry of Health recommended that municipalities apply the Pfizer vaccine to replace the second dose of the AstraZeneca vaccine. The Ministry considers that in emergencies or in exceptional situations, due to specific contraindication or absence of the immunizing agent, the heterologous combination of these two vaccine platforms can be made. The Ministry of Health had already recommended the interchangeability of vaccines for pregnant women who took the first dose of AstraZeneca and must complete the vaccination schedule with a vaccine that is not based on an adenovirus platform, such as the vaccine from AstraZeneca, Janssen and Sputnik V In this case, the Ministry recommends the use of a second dose of Pfizer, based on messenger RNA technology, or CoronaVac, based on an inactivated virus platform.
A study de security analysis published in the magazine Lancet on 12/05/2021, observed an increase in systemic reactogenicity after the booster dose reported by participants in heterologous vaccine schedules compared to homologous vaccine schedules. Adverse effects were considered mild, occurred within 48 hours after the second dose and were controlled with the use of paracetamol. Reactogenicity, although more intense in this study, is of little clinical relevance and can be modulated by modifying the time between doses
Another article published on 14/07/2021 in the magazine Nature Medicine, involving 87 people, showed that antibody production is higher in people who received a first dose of the AstraZeneca vaccine, followed by a second dose of Pfizer's messenger RNA vaccine.
Um most recent article, published in the magazine Lancet on 06/08/2021, involved 830 people with an average age of 57,8 years. The study was single-blind and randomized and evaluated the safety, reactogenicity and immunogenicity of the heterologous combination and showed good results in terms of safety and immunogenicity with the combination of regimens involving a first dose of the AstraZeneca vaccine followed by a second dose of the AstraZeneca vaccine. Pfizer, with an initial booster interval of 4 weeks. Despite some study limitations, this combination of viral vector and mRNA vaccines, can increase flexibility in mass vaccination campaigns, especially for vaccines being deployed in low- and middle-income countries.
TThird dose on the way?
US health authorities have authorized the application of a third dose of the highly technological vaccines from Pfizer and Moderna for immunosuppressed people or who have received an organ transplant, understanding that these groups may benefit. At the moment, the American FDA understands that this measure is not necessary for the entire elderly population. There, the Pfizer and Moderna vaccines have been used in the population over 12 years of age. Both France and Germany are adopting a similar strategy. I understand that most likely in the future, this strategy can be applied to all populations, but at the moment, it is essential to accelerate the application of two doses or a single dose of the Janssen vaccine to as many people as possible.
I think that expanding vaccination coverage is now more important than applying a third dose to priority groups. The population needs to understand that even vaccinated people can be infected by the Gamma variants (originally detected in Brazil) and Delta virus. Vaccines work and protect, but they are not infallible. To reduce the circulation of the virus and the emergence of new variants, we have to vaccinate faster with the first dose or a single dose of the Janssen vaccine and ensure that people who took the first dose return for the second dose on the scheduled date.
It is necessary to encourage people to maintain non-pharmacological measures and test as many people as possible, advising those infected and their immediate contacts to remain isolated for a few days and monitor the appearance of variants of concern. We need greater empathy and social responsibility on the part of the population, to be able to overcome this health crisis.
Another very important point before thinking about a possible third dose is vaccinating populations in low-income countries, which do not have money to buy vaccines, nor do they have local infrastructure for vaccine production. At the moment, we are seeing huge disparities in the global vaccination process, with only 1,2% of vulnerable populations in low-income countries have taken at least one dose of vaccines. We will not get rid of the virus in this bleak scenario. We will only be safe when the world is safe.
CoronaVac: third dose increases protection
results of studies of homologous vaccination involving the application of a third dose of CoronaVac vaccine in 540 volunteers (in addition to another 30 in the placebo group) aged 18 to 59 years who took two doses of CoronaVac, show an increase in immunity against coronavirus with a considerable increase of three to five times the antibody level. One another study, controlled, randomized and double-blind, shows the positive impact of a third dose of CoronaVac on 303 people over 60 years of age, with an increase in antibody levels in the participants' blood by up to seven times. The works were published on the platform medRxiv in the shape of preprints, still unevaluated by other scientists. The third dose of the vaccine proved safe for all participants, including the elderly. We must highlight that these two studies only evaluated the levels of neutralizing antibodies, which we have already mentioned countless times as being important, but are not the only types of protective response from the immune system, which also includes T lymphocytes.
These studies reinforce the effectiveness of CoronaVac in the two-dose schedule and that the level of protection is increased with a booster dose. We still need to accumulate sufficient scientific evidence to prove benefits from applying the third dose, but preliminary results are promising in guiding us in that direction.
It is essential to reduce cases of community transmission with mass testing, as the majority of infected people are asymptomatic or have few symptoms. What will allow Covid to be controlled and cases of contagion to be reduced is broad vaccination coverage, because the more people vaccinated, the more people protected, the lower the circulation of the virus, the lower the number of infected people and the lower the number of deaths. Those who are vaccinated protect everyone around them, they also protect those who are not vaccinated.
ABOUT NEW VARIANTS
Vaccine escape
An important issue at this time is the discussion about the need to update the vaccines in use for Covid-19, so that we can more effectively combat new variants emerging and prevent the virus from escaping the immunity produced by vaccines. All of the vaccines in use today were developed when another variant of the virus was circulating around the world. Delta is more transmissible, if people are not careful, it will infect the unvaccinated and those who have already been infected by other variants and will infect older people who have only taken the first dose or who have already taken both doses, regardless of the vaccines . In the scenario of slow vaccination, especially in poorer countries, another variant may emerge, leading to vaccine escape. The essential thing is to quickly vaccinate all populations in countries with a low vaccination rate.
But scientists are exploring the possibilities of redesigning current, first-generation vaccines so that we can more effectively combat emerging variants. Right now, the most efficient way to combat the threat of emerging variants is to quickly vaccinate as many people as possible with current vaccines. We still do not know how many antibodies we need to fight the virus and whether the new updated vaccine platforms will be sufficient to increase the effectiveness of these vaccines against the new variants.
Neutralizing antibodies
An important question is how will new versions of vaccines be tested? It is unclear how much clinical data would be needed to approve an updated Covid-19 vaccine. Scientists should aim to find “correlates of protection”, such as a certain level of neutralizing antibodies, which could provide a marker for protection against Covid-19. Even in the context that a robust correlate does not appear, if the vaccine produces levels of antibodies similar to those of first-generation vaccines, it will be an important achievement. This way, it is not necessary to wait for study participants to be infected with the new variants to know if the updated vaccines are working, simply measuring immune responses after each dose. Another important question is: how will people respond to updated vaccines if they have already been immunized with first-generation Covid-19 vaccines? Will people already vaccinated show a more robust protective response?
Moderna is updating its messenger RNA vaccine and Johnson & Johnson is also looking to update its single-shot coronavirus vaccine. Perhaps something to consider is developing a vaccine that targets several sites on several viral proteins, rather than just focusing on the Spike protein, which would be different from what was done in this first generation of vaccines against Covid-10, which aim to produce antibodies. neutralizing against a specific part of the virus' Spike protein.
More about the Delta variant
The Delta variant has greater transmission capacity, as already mentioned this article e in this other article and leaves infected people, both vaccinated and unvaccinated, with a viral load around 1000 times higher in the upper airways when compared to the Alpha variant. These characteristics cause vaccines to lose some of their effectiveness against Delta, especially after just the first dose. The symptoms caused by Delta infection, such as headache, sore throat, runny nose and fever, complicate the scenario, as they can lead people to confuse them with flu symptoms and relax non-pharmacological health control measures, transmitting the virus. to other people around you.
The world is observing that the Delta variant is surpassing other variants in circulation, leading to an increase in the number of infection cases and consequently deaths. This is worrying, as we only have around 23,43% of the Brazilian population with the complete vaccination schedule, everything that Delta dreamed of and wants. Gamma is still the dominant variant here, it will fight with the Delta variant for space and in this process of natural evolution, we have to wait. But let's hope that natural selection leading to more transmissible mutant forms of the virus can be controlled by vaccines.
Observation: This text is the responsibility of the author and does not necessarily reflect the opinion of Unicamp.
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