by
Nick Nunes
Advances in technology and medicine are the reasons why the COVID-19 vaccines have been created and put on the market so quickly.
This explanation came from Clinical Scientist Dr Kim Quimby, Chair of the UWI Barbados Association of Medical Practitioners CME Committee and a member of the Barbados Medical Council Committee. She was speaking during webinar produced by the Sagicor Cave Hill School of Business and Management entitled COVID-19Debunking Myths of the Jab.
“An analogy would be if you were going to Bridgetown 50 years ago you would have to walk or go by donkey cart and it would take you 12 hours to get you there. But now, you can hop in a car and it would take you less than half an hour to get there. It is not that things were rushed, it is that we have new advances to help us to do things a lot faster,” she explained in her session which was specifically geared towards explaining the science behind the virus and the science behind the vaccines available.
Acknowledging that people have been inundated with information from all kinds of sources, Dr Quimby explained the unique and infectious nature of the COVID-19 virus.
“The SARS CoV-2 virus has spike proteins along its exterior,” she explained. “Spike proteins bind to the ACE-2 receptor, which is on our human cells, and the virus uses that receptor to enter our cells. Once within our cells, the virus releases its mRNA. RNA is the genetic code for the virus just like humans have DNA. The RNA says what the device should look like and then uses our own machinery within our cells. It uses our machinery to make proteins out of the RNA. It rebuilds the virus, basically, and then the virus breaks out usually killing the cell in the process. The important thing we need to know is how to fight this novel virus,” she said, adding the virus replicates itself within our cells and spreads.
Quimby’s presentation illustrated how our dendritic cells, which are phagocytes (meaning they eat other cells), consume the virus when it enters our system. It then cuts the virus up into pieces and presents it to T cells that help the rest of the immune system to become activated.
The T cells will activate more dendritic cells which will then go back and eat more viruses. The T cells also activate B cells. The B cells have Y shaped molecules called antibodies or immunoglobulins. Once the B cells are activated, they multiply. Quimby added, “Sometimes when you get an infection, you can feel the lymph nodes under your neck or behind your ears swelling up, that is because your immune system is becoming activated.
Once the cells multiply they release a lot of the Y-shaped antibodies. These antibodies will then bind to the virus and kill the virus in several different mechanisms.
Quimby, who has presented outcomes of her research at multiple local, regional, and international scientific meetings during her career, explained there are three major types of vaccines: the viral vector which is the AstraZeneca Sputnik and Janssen, there is the mRNA vaccine which is Moderna and Pfizer, and the vaccine that is part of the protein or outer shell which can be a protein subunit, like Novax or an inactivated virus which has been heat-killed and cannot replicate, like the Sinovac.
“The mRNA vaccine uses the mRNA of the virus and is surrounded by a lipid bilayer which is two layers of fat. The mRNA within this lipid bilayer is not a code for the entire virus, just the spike protein which is the protein that the virus uses to enter the cells. When this vaccine is introduced to the system, the dendritic cells then eat the vaccine. The process is then the same if it were an infection the mRNA is released and it uses our apparatus to make more of itself but not the full virus as it only has the code for the spike protein,” she said.
“The spike protein is then presented and recognised by the T cell which then helps the dendritic cells and the B cells which produce the antibodies. Then, if you are infected with the real virus the antibodies are already there preformed and ready to destroy the virus.”
The viral vector vaccines use an adenovirus, which is a flu virus that has been gutted and implanted with the DNA for the coronavirus.
“DNA is easier to work with,” Quimby asserted. “The RNA vaccines have to be stored at very low temperatures because RNA is very fragile. DNA is very robust which is why they use the DNA for the coronavirus spike protein. When you receive this vaccine, the dendritic cells then take the same measures. The dendritic cells eat the vaccine and then the DNA is in the nucleus of the cell and is converted from DNA to RNA within the cell. Then the RNA comes out of the nucleus of the cell and uses our machinery to build spike proteins and present on the outside where the T cells then activate and help the dendritic cells and the B cells then produce the antibodies which sit there and wait in case you get a real infection.”
She continued: “The third type of vaccine actually gives you the protein of the virus. This vaccine is either a subunit, which means they cut off part of the virus and use that, or they use a killed or inactivated virus. Once this vaccine is injected, the dendritic cells consume it. There is no converting necessary as the protein is already present. The protein is then presented to the T cells who then helped the rest of the immune system become activated in the same way as the other vaccines.”
All of the vaccines have different preparations, slightly different intracellular processes, but the same outcome of an activated immune response.
Each vaccine trial involved over 30,000 volunteers that were split randomly into two groups: those that would receive the vaccine and those who would receive a placebo. For Moderna, Pfizer, AstraZeneca, and Janssen, the endpoint of their trials was to prevent symptomatic COVID-19.
This means that after receiving the vaccine, only those who presented symptoms were requested to revisit to test for COVID-19. In the Moderna group, 185 people in the placebo group were positive for symptomatic COVID-19 while only 11 from the vaccine group experienced symptoms. This gives Moderna a 94 per cent efficacy.
In the Moderna trials, there were five deaths. Of those, three were in the placebo group and two in the vaccine group not related to the vaccine. One person died of a heart attack and another committed suicide. The Moderna vaccine reported efficacy against the UK strain but decreased efficacy against the South Africa strain.
The Pfizer vaccine efficacy was found to be 95 per cent and there were two deaths not related to the vaccination. Its efficacy was the same as the Moderna vaccine against the UK and the South Africa strains.
During the AstraZeneca vaccine trials, some persons got a standard-dose/ standard-dose while some persons got a low-dose/standard-dose. They are doing more trials to look into the low-dose standard dose method of vaccination. The standard-dose/standard-dose had an efficacy of 76% which is the method that has been rolled out.
“To put things into perspective, the flu vaccine only has a 40 per cent efficacy rate. The WHO will okay anything between 30 and 50 per cent efficacy,” said Quimby, who is also the Curriculum Coordinator of the Caribbean Cytometry and Analytical Society.
“The side effects were one haemolytic anaemia but that was in the placebo group, one transverse myelitis which is a problem with the nerves, and one person who had a fever over 40°C but it subsided and it is not certain which group that person was in.”
The efficacy against the UK and South Africa strains were the same as the previous two vaccines. AstraZeneca also looked at asymptomatic COVID. This swabbed all of their participants whether they were symptomatic or not. Tt showed that the efficacy against nonsymptomatic COVID was null at 16 per cent.
The Sputnik vaccine looked at prevention of all COVID. After the second shot of the Sputnik vaccine, everyone was swabbed and the efficacy was 91.6 per cent which means the Sputnik vaccine prevents you from getting COVID, not just symptomatic COVID.
There were four deaths unrelated to the vaccination and the reports suggest efficacy against the UK strain but there is no data against South Africa strain. This trial took place in Russia with 98 per cent white population and two per cent mixed and the level of NCDs was not well represented within this trial.
The final vaccine Quimby spoke about was the Janssen vaccine from Johnson and Johnson. “This information has not yet been published but is just from a report. They also looked at prevention of symptomatic COVID. They gave an efficacy of 66 per cent and presented no safety data on their website but state that it was efficacious against the South African variant and only required a single vaccination shot.”
Preventing symptomatic COVID-19 means that once you get the vaccine you are protected against becoming ill but you still need to practice social distancing, wearing masks and washing hands because you may still infect others that are not protected. New data from AstraZeneca suggests that the transmission of COVID-19 has been reduced by two-thirds with their vaccine,” Dr Quimby revealed.
