COVID -19 : 3rd Wave, Delta Variant And Vaccine Efficacy - THE DAILY CRUCIBLE



Thursday, July 29, 2021

COVID -19 : 3rd Wave, Delta Variant And Vaccine Efficacy


By Cpt. Abdoulaye Dia, PhD

The ongoing 3rd wave of COVID-19 in Africa will be more deadly than the previous ones. Unlike the first wave that was more brutal because of the surprise effect, the following waves are less brutal because we see them coming. But they have a more significant impact because they are longer and more deadly. 

This phenomenon is explained by the fact that the virus has widely spread with new and more contagious variants, and barrier measures are observed less and less. Local authorities must reinstate restrictions as soon as possible to help hospitals and healthcare workers cope with the incoming wave of patients. 

These restrictions must be more robust in areas of tension. It may even be necessary to call on the experience and expertise of the military forces in logistics and crisis management: construction of field hospitals to increase the bed capacity and strengthen the supply chains. 

In addition, authorities must put a great emphasis on raising awareness. Skepticism towards COVID vaccines is a global public health concern. So, we must understand the population’s fear and put forward scientific arguments to dismantle the conspiracy theories.

Vaccination is effective against threats of the Delta variant
First of all, one should know that mutations (variants) are a natural evolution of viruses, which allows them to survive. All living beings (humans, animals, microbes, plants, etc.) seek to perpetuate their species by adapting. 

When a virus circulates widely in a population and causes many infections, the likelihood of the virus mutating increases because the more opportunities a virus has to spread, the more it replicates (multiplies), and the more opportunities it has to change (mutations). 

Since the start of the pandemic, thousands of mutations (variants) have been detected. But, there are only a few variants that have raised concerns,  including the English (Alpha), South African (Beta), Brazilian (Gamma) variants, and now the Delta variant discovered in India.

The English variant was 50% more contagious than the original virus (starting virus). The Delta variant is 50% more contagious than its English variant. This makes the Delta variant 100% more contagious than the original virus. 

In an environment where no one is vaccinated or respects the barrier measure, the average person infected with the original strain will infect 2.5 other people. In the same environment, Delta would spread from one person to maybe 3.5 or 4 other people. 

According to a recent Chinese study pre-published on July 12 on the medRxiv site, the Delta variant has a shorter incubation period: 4 days instead of 6 days for the original strain. According to the same study, the viral load of the Delta variant is 1260 times higher than that of the original strain. 

Thus, the Delta variant is more contagious at the early stage of contamination and can lead to “hidden” contaminations even before the appearance of the first symptoms. That is the reason for the global explosion of contaminations. 

In addition to being more contagious, the Delta variant may be more virulent, causing many more severe cases in unvaccinated people . The good news is that the vaccination is effective against the Delta variant. People must understand that vaccination is the key to overcome this health crisis. Vaccination has three objectives. 

The first is to protect the individual. The second is to protect the population (herd immunity) by cutting off the chain of transmission, and the third is to eradicate the pathogen. This last objective is more difficult to achieve. At the individual level, the vaccine has two purposes. The first is to prevent a specific disease. The second is to prevent severe forms of the disease in case the individual gets ill. 

In fact, in some people, the immune response induced by vaccination is not strong enough to prevent the individual from becoming ill, but it is sufficient to prevent a severe form of the disease. 

This second purpose of vaccination is fundamental in the current pandemic context. Preventing severe forms of COVID can decrease both hospitalization and death rates. So, if the vaccination fails to prevent you from catching COVID, vaccination can prevent you from the severe COVID form caused by the Delta variant. It was shown that available vaccines protect less against symptomatic forms of COVID, but they are effective up to 96% against severe forms of COVID. 

In many countries such as France, Israel, and England, contaminations are on the rise, but hospitalizations remain stable thanks to vaccination. In the United States, there is a surge in COVID cases and deaths among unvaccinated populations. More than 99% of the latest deaths were unvaccinated. That is what prompted the Centers for Disease Control and Prevention (CDC) director, Dr. Rochelle Walensky, to say that this pandemic is becoming “the pandemic of the unvaccinated.”  

That is why the World Health Organization (WHO) recommends vaccination with all its approved vaccines. People must be vaccinated en masse to achieve herd immunity. Vaccination will help control the threat of the Delta variant and prevent the emergence of new variants to stop the pandemic. 

I believe the vaccine will be more and more available. After vaccinating more than 50% of their population, developed countries have a genuine interest in helping developing countries vaccinate their people. They would not want new dangerous variants to emerge in developing countries to compromise the herd immunity acquired in developed countries. 

After being vaccinated, people must maintain barrier measures (wearing a mask, social distancing) as long as the epidemic persists and most of the population is not vaccinated because we cannot be 100% sure to be immunized against COVID after taking the vaccine.

Need a third dose of vaccine?

Pfizer-BioNTech, the leading manufacturer of an anti-COVID vaccine, recommends the 3rd dose to deal with the new variants. This recommendation seems more like a commercial announcement than a scientific fact. 

The US CDC agencies and the Food and Drug Administration (FDA) contradicted this recommendation with the following statement: “Americans who have been fully vaccinated do not need a booster shot at this time...FDA, CDC, and NIH are engaged in a science-based, rigorous process to consider whether or when a booster might be necessary. 

"We continue to review any new data as it becomes available and will keep the public informed. We are prepared for booster doses if and when the science demonstrates that they are needed”.

One must admit that this recommendation from Pfizer-BioNTech is premature because there is not yet enough data or scientific publications to support this idea. Pfizer relied on an Israeli study that showed a drop in antibodies six months after vaccination.

However, antibodies are not the only components of the immune system. In addition to the antibodies produced by lymphocytes B, the adaptative immune response also involves killer cells called lymphocytes T which attack infected cells, not to mention the innate immune response, which always plays its role as the first barrier. 

Antibodies decline naturally over time. One can take the example of the vaccine against yellow fever. The antibodies even end up being undetectable over time, yet this vaccine offers permanent immunity (protection for life). However, a 3rd booster dose may be considered for immunosuppressed patients.

CPT Abdoulaye Dia, PhD, is a serving US Marine and Global Health Practitioner/Researcher at Trident University International, Cypress, California USA.

No comments:

Post a Comment