Our COVID-19 vaccines are good-but there is one way they can be better

Healthcare professionals are holding a vial of AstraZeneca’s COVID-19 vaccine at the Vaccination Center in Ronquières, Belgium, on April 6, 2021. Photo: Reuters / Yves Herman / File Photo

Recently, in some developed countries such as Israel, the United States and the United Kingdom, there have been some public talks about the presumed “failure” of the COVID-19 vaccine.

according to New report The US Centers for Disease Control and Prevention (CDC) found that 346 (74%) of 469 COVID-19 people were fully vaccinated after several major public events in Massachusetts. .. This discovery forced the CDC to make a U-turn on its recommendations, encouraging vaccinated people. Mask Indoors where the delta variant is widespread.

We know The delta variant of the new coronavirus is about twice as contagious and induces 1,000 times the viral load of the “original” strain. It also has a short incubation period, which results in people infected with this mutant being tested positive immediately after exposure.This variant is also likely to breakthrough It is the protection provided by the vaccine and can cause more serious illness than all other known variants.

There was a study from the Israeli Ministry of Health on the limited protection that the Pfizer vaccine provides against symptomatic infections of delta mutants.Similarly, a report from UK Public Health Services Two doses of both the Pfizer and AstraZeneca vaccines significantly reduce the defense against symptomatic infections of the Delta variant compared to the Alpha variant.Pfizer itself admits Decline faster The effectiveness of the vaccine in Israel.

Main purpose

Most of the world’s existing crops of COVID-19 vaccine provide high protection against severe COVID-19, hospitalization and mortality. They also provide considerable protection against symptomatic diseases and moderate protection against infections and transmission of the disease.Axiomically, vaccines contribute little to the fight against the frequent surge Of the SARS-CoV-2 virus.

What should our main purpose be: to resist an ongoing outbreak or avoid hospitalization and death?

An important feature of public health and the dynamics of viral infections is a serious illness that requires hospitalization and can be fatal, indicating that it contributes little to the transmission of the virus in the population. It also does not significantly affect the evolution of the virus. The main choice of the latter is communication. Therefore, preventing serious illness and death brings immeasurable benefits to the individual, but in itself contributes little to ending the pandemic itself.

Another basic lesson is that there are two widespread interventions to manage infections. Prevention and treatment. Vaccination is prophylactic, but the (antiviral) drugs used to treat and prevent severe illness and death are therapeutic. In the case of a new viral pandemic, the vaccine should ideally be able to stop the ongoing transmission of the virus through the population. Current generation COVID-19 vaccines do not provide significant protection for this form.

The CDC report, labeled “preliminary,” states that SARS-CoV-2 can thrive in the respiratory tract of vaccinated people, even asymptomatic, based on the health report available at the time of editing. Stated. He also reported that there was no difference in the amount of viral particles present in the nasopharynx of fully vaccinated and unvaccinated individuals.

Today, we know that we need a vaccine that can provide bactericidal immunity, an immunity that blocks the transmission of the virus from one vaccinated person to another. also People who have not been vaccinated.

Even WHO made the mistake of focusing the primary endpoint of the COVID-19 vaccine trial on the prevention of asymptomatic disease and symptomatic disease rather than preventing infection by vaccinated people. ..

Assessing vaccine efficacy is complex for many diseases, especially for COVID-19, which has a well-developed basic understanding of pathogens. Potential endpoints of effective vaccines include reducing infections in individuals, reducing the severity of the disease, or reducing infections within a population.

In September 2020, WHO At least 50% effectiveness It is an important primary endpoint for symptomatic diseases and has reduced the effect of immunization on infection rates under the indirect effects of vaccination. In the case of stable endemic diseases such as hepatitis A, hepatitis B, and chickenpox, personal protection alone can be justified, but as new pathogens rage, the effects of vaccines on the infectious dynamics of the virus need to be prioritized. I have.

Why did WHO overlook the effects of vaccines on infections? There are several possibilities. First, WHO was probably not confident in the success of the new vaccine against the new coronavirus (no SARS-1 and MERS approved vaccines). Second, due to the lack of effective therapeutic intervention, WHO may have determined that protection against serious illness is more important. Third, it is far more labor-intensive to detect and capture asymptomatic infections with continuous sampling (such as weekly swab exercises) than to identify symptomatic illnesses in vaccinated individuals.

However, vaccines that have less impact on the clinical course but reduce the infectivity of SARS-CoV-2 may still be very valuable interventions at the population level.

Can’t vaccinate our way

One of the main goals of large-scale vaccination is to achieve herd immunity against pathogens. However, the vaccines we have available cannot do this. Until very recently, experts have raised the vaccination rate by 70% as a herd immunity threshold. Now it can be much higher.

The standard calculation of the herd immunity threshold is (1 /E) × (1 – 1 / Ro). E Is the effectiveness of the vaccine to reduce infection and Ro is the basic fertility. If Ro is high – 5 to 9.5 in US Delta Variant1Let’s assume 6 – and the vaccine is 85% effective in preventing infection, for example, 98% of the population will need to be vaccinated. Most countries cannot achieve such high coverage.

However, if the vaccine is less effective When Ro is higher, both of which are likely scenarios worldwide, but vaccine herd immunity is not possible. Moreover, the delta variant is not the last variant to appear.I have Real potential New, more contagious strains may emerge, leading to the avoidance of a wider range of diseases and vaccines.

Currently, vaccination is not possible to get out of the pandemic. Instead, getting out of the pandemic requires both vaccines and other non-pharmacological public health measures such as masking, social distance, and assembly restrictions.

Escape?

To be fair, developing a vaccine that can effectively stop infection, that is, provide bactericidal immunity, is a daunting task. It can be simplified to some extent by using a combination of vaccines or by investing in vaccine development. Universal coronavirus vaccine (This is scientifically feasible).

In the former case, researchers have found mucosal vaccines (intranasal injections to stop the virus at the entrance), existing parenteral vaccines (to reduce the severity of the disease), and older live attenuated vaccines (to enhance congenitality). ) You can test the efficacy and safety of the vaccine immunity).

or, Variant proof A universal coronavirus vaccine that can stop the infection is also very viable, but is not a priority at this time.

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The evolution of the new coronavirus demonstrates the importance of rational vaccine design.It’s also not the last pandemic virus – there may be SARS-CoV-3 and SARS-CoV-4 Similarly..

So, instead of staying in the prevention of serious illnesses, invest in the development of vaccines that better serve the purpose of preventive medicine and help stop viral infections and kill surges.

Dr. Vipin Vashishtha, MD, FIAP are pediatricians at BIJNOR’s Mangla Hospital and Research Center.