#LongReadAhead: Vaccines Efficacy And Effectiveness Explained

THE arrival of the coronavirus on our shores has to a larger extent planted an appetite for reading and commenting around health-related issues even amongst non-medical people. All of a sudden everyone is now a public health or medical analyst and this is largely due to information gaps present in our communities.

By Michael Gwarisa

The World Health Organisation (WHO) identified information and communication as a key pillar to the pandemic response amongst the eight pillars the world heath body has set. However, when not managed and disseminated well, information can be very harmful and could undermine and stand in the way of attaining positive health outcomes.  Ever since the pandemic was reported, there has been an outbreak of misinformation at the back of conspiracy theories and falsehoods that have been making rounds especially on social media platforms

Zimbabwe has already commenced administering doses of COVID-19 of the SINOPHARM and SNINOVAC both Chinese manufactured vaccines and the COVAXIN from India. However, the prevailing infordemic has slowed down uptake of these vaccines even though numbers of those getting vaccines are slowly creeping up now.  To date, majority of people especially in Zimbabwe still confuse the terms Efficacy and Effectiveness. There is belief that a vaccine whose efficacy is around 50% is less effective as compared to a vaccine which has say an efficacy rate of 95%. Is this the case though?

To clarify on issues around vaccines and the Sinopharm vaccine’s effectiveness, safety and efficacy, renowned Immunologist and medical expert, Dr Tinashe Gede took time to sit down with local Editors and Station managers during a non-formal gathering that was organized by the Zimbabwe Editors Forum (ZINEF) in collaboration with the Humanitarian Information Facilitation Center (HIFIC) to unpack and demystify COVID-19 Vaccines myths and misconceptions.

Before we get into the depth of the article, maybe you might want to know who Dr Gede is. Dr Gede is a Harare based Physician and former lecturer in the department of medicine at the University of Zimbabwe (UZ). He graduated from UZ in 2007 before proceeding to Oxford University in the United Kingdom (UK) for an MSc in Immunology as well as Masters in Public Health before pursuing training in Clinical Medicine initially at the John Radcliffe Hospital in Oxford and advanced specialist training in Internal Medicine at the University of Pittsburg in the USA with special training in Critical Care Medicine. He was accredited as Diplomate of the American Board of Internal Medicine and is a member of Royal College of Physicians in England. He also runs Private practice in Harare as a Specialist Physician.

Unpacking Vaccines with Dr Gede:

History Of Vaccines

Vaccines and infectious diseases are not a new thing. If you go back in History, nothing has shaped mankind more than infections. Infections that probably have a long-standing history was Small Pox which cumulatively killed more than 50 million people and estimates are probably close to 500 million people at different time points in history may have died from Small pox and it became the first infection that was completely eradicated through vaccination.

If you go to the earliest reports of when vaccination first became a thing, historical reports go back to the ancient Buddhist Monks in China from about the 12th Century already carrying out variolation on Small Pox vaccination. Most of us modern scientists look to a guy called Edward Jenner as the father of modern-day vaccination around 1796 and the technology that he is famous for was actually a technology that was widely practiced in Africa where it was known that if you had somebody with Small Pox and you took the Cow Pox vaccine and sort of spread it around or inoculated it, the infection you got was very minimal but the protection you got protected you against severe infection in the future. That process of variolation became the birth of modern-day vaccination.

Developing a Vaccine Explained In Simple Terms:

In a very simplistic way when developing a vaccine, what you need to do is identify an organism and figure out a way to somewhat make it less pathogenic. Either kill it completely or inactivate it or weaken it so that when you introduce it to the body, because it looks exactly like the virulent strain, the body learns to fight it. So, it’s a bit like coaching for a major football game. You do some training drills, you study your opponent so that when the moment to perform comes, you are better prepared for it. Most of the old vaccines, depended on very old technology where you took an organism you either used it whole inactivated or attenuate it and you vaccinate it.

For at least the past 15 years, there has been a gradual use of modern-day scientific developments around what we call genetic engineering in molecular biology where you don’t necessarily need the actual organism but you need to know what its genetic material looks like. You can almost make a part of the virus protein in laboratory and use that as a vaccine. Now that technology is new off the bloc and for the first time, it’s being used against COVID-19. Because of the concept of genetic manipulation that has somehow led to concerns whether we are cloning people or whether people are putting DNA microchips in bodies? We also have traditional old school vaccines such as those that were used on Polio and Hepatitis A. that’s the same technology that was used to develop the Sinopharm that we are using here in Zimbabwe. In Zimbabwe at the moment there are at least four approved vaccines but we have two vaccines the Sinopharm and Sinovac that are being widely rolled out in the country. We also received a donation of COVAXIN from India and these three (Sinopharm, Sinovac and COVAXIN) are just the same, there are all made from inactivated vaccines.

Vaccine Platforms Available

We have about three vaccine platforms available globally at the moment. These include the Inactivated vaccines (e.g Sinopharm, Sinovac, COVAXIN), we have the RNA and MRNA and the Viral Vector Vaccines (e.g Johnson & Johnson and AstraZeneca.) When developing inactivated vaccines such as the SINOPHARM, SINOVAC or COVAXIN, what you basically need to do is go to somebody who has COVID-19, take a swab, go in the laboratory and then you grow the virus in a petri-dish. Essentially using the cell lines. There is something called the Vero cell lines which is obtained from green monkeys in Africa so it’s been used for the last 30 years to basically multiply viruses. Once you have got a sufficient number of virus, you then go through a process called passagning or weakening so that it doesn’t replicate for itself. The virus essentially dies in terms of its replicative capacity but its structure looks exactly the same. Then afterwards, they add something called aluminum hydroxide which we call an adjuvant. Once you have altered the virus, its ability to excite the system is not nearly as good as when it is fully live. So you have to stimulate the immune response to the adjuvant which is this thing called Alum and then that combination is what we basically calculate a dose and then inject into humans. The humans then learn to make an immune response. Those are the inactivated vaccines.

Other parts of the word for different reasons, have not gone the same route as the Sinopharm, Sinovac and COVAXIN. In North America they have what are called RNA or MRNA vaccines where you basically take a snip of the genetic material of the vaccine and you coat it with a fat molecule and then you inject. The hope is once you inject it, the body reads the genetic material of the virus and makes a virus protein called the spike protein and that antibody it makes is what protects you. The other class of vaccines are what are called viral vector vaccines. In this case, they take the genetic material then they join it together with the genetic material of a common cold virus. There is a family of viruses called adenoviruses. The group in Oxford chose a Chimpanzee adenovirus, infect you with it but it carries a genetic material for COVID-19. So, as you fight the Chimpanzee adenovirus, you are seeing the genetic proteins of COVID-19 strain. The Russians  when they developed the Suptnik V used a virus called adenovirus 26 which is also what Johnson & Johnson used.

Which Vaccine Platforms Have Stood The Test Of Time?

The inactivated vaccines however have been available for the longest possible time. Some of the reasons behind this is that traditionally, we didn’t have the science for genetic manipulation so we couldn’t make the newer vaccine constructs. The inactivated vaccines have been around for well over 150 years. The Viral Vector Vaccines are relatively newer but of the three platforms, they are probably the second most mature. There is only one other viral vector-based vaccines that has been approved for human use which is the Ebola vaccine. The MRNA vaccines are seeing use in human trials and in human vaccination for the very first time with COVID-19.

There is a group of vaccines that is probably just as common as the inactivated ones called the Attenuated vaccines. Attenuated means the organisms is still alive and able to somewhat replicate but it’s very severely weakened. Because we don’t have an effective treatment for COVID-19 and we don’t know whether it can potentially mutate back to an aggressive strain, there has been a sense that using a weakened COVID-19 can potentially lead to a disaster if the virus mutates back to an aggressive strain. We know that because when the Polio vaccine was first developed, (NB// there are two kinds of Polio vaccines what’s called the Salt Vaccine which is a killed vaccine like the Sinopharm and there is a Sabin or live vaccine like the one that’s dropped in mouth that the kids are getting now), the process of inactivation or attenuation wasn’t complete enough so there was an outbreak of vaccine induced Polio and ultimately, lots of people became disabled and some actually died. So, there is not a single attenuated vaccine that’s available for use yet.

What Is Vaccine Efficacy and Vaccine Effectiveness?

There are these two words, Efficacy and Effectiveness. Efficacy essentially means that in a controlled environment like in clinical trials, you have got one group getting a dummy or a Placebo and another one getting a vaccine and you basically make sure that everybody who is randomized to get the vaccine gets the vaccine. You then follow them up for a period of time. In the COVID-19 vaccine development space, because its vaccine is being developed in somewhat of an emergency, most of the vaccine trials would follow them up actively for one month. At that one month, what you would look for is to say how many fully vaccinated people get infected versus how many who got a Placebo get infected. In other words, is there a difference in your level of protection?

If you look at the Mordena trial for example, 44,000 people in the trial, on follow-up, about six of the vaccinated people got infected versus about 75 non vaccinated. So, what they assume is that if you had not been vaccinated, you would see 70% because it’s a random population. So, the protection is the 67 who did not go on to get infection. So you then say 67 out 74 and you calculate a percentage protection Efficacy. That’s is why they would say its 94% effective. The inference statistically is if you roll it out at a broader level and it maintains the same level of protection, your likelihood of getting infected is reduced by 95%.

Sinopharm and Sinovac Efficacy and Effectiveness:

Coming to the Chinese vaccines. There are two vaccines, one which was made by Sinopharm and another one which was made by Sinovac. One is a state sanctioned vaccine manufacturing company and one is a private company. Because China’s Public Health interventions have been very effective at limiting COVID-19 transmission, by the time they had the vaccines, there really wasn’t any active infection happening. So, if you are trying to demonstrate efficacy, you need some level of challenge to see how effective the vaccine will be. So China had to look for countries that had active infection going on. With the Sinovac, they chose Brazil, there was a group in Pakistan, there was a group in Turkey and there was a group in the United Arab Emirates (UAE).

The reported Efficacy was different for different countries. The Turks reported an Efficacy of 86%, Brazilians had a bit of difficulty reporting their data. First in Brazil it was 75% then a few days later it was revised down to 50.7% then after a few days it was 78%, so it was very confusing. What essentially happened with the Brazilians which was very different was that every other vaccine trail enrolled routine members of the population and then they followed them up in their own communities. However, the Brazilians got 15,000 doses of vaccines, chose nurses and doctors and said that’s it, you are going to be our first trial group. Every week, because they were working in the Hospitals, they were getting Polymerase Chain Reaction (PCR) tests. What they found is that they were a lot more infections in the vaccinated people which is where the 50.7% efficacy came from.

When you re-analyze and say what about people who actually felt sick, the efficacy at preventing illness was 78%. So, the 50.7% is an efficacy against any infection including asymptomatic infection. Now it only became clear why the Brazilian data was very different when we saw data from the AstraZeneca and Johnson & Johnson vaccines. By the time the Sinovac trial was done in Brazil, there was a new strain of COVID-19 that was circulating in Brazil called the P.1 Variant which is a lot more infectious than the wild type strain. That sort of perceived loss of efficacy in Brazil was replicated with AstraZeneca and was also replicated with J&J. When you look at trials in South Africa, there have not been very encouraging because the SA variant is a lot more virulent. The simple way to put it is that If you put a Durawall around your house in a place like Borrowdale brook where its  a gated community, chances of buglers and thieves breaking in are very low as compared to someone who puts a Durawall around a house in Epworth. In Epworth chances are slim that you will go for months without anyone jumping into that Durawall.

In a place where you have a very aggressive strain with lots of community transmission, your efficacy will be lower whereas in a place where you have got a weaker strain with very minimum transmission, you can get the sense that your vaccine is very effective. The WHO set a consensus committee to say how much protection should a vaccine have for it to be licensed and that number was set at 50%. The reason why it was set at 50% was historically in wealthy countries where they vaccinate for flu every year, we know that the average flu vaccine that’s given every year has an efficacy between 40-60%. So you don’t need to prevent infection necessarily but you need to prevent severe infection and death and all the approved vaccines have proven to be almost 100% effective against severe infection and certainly 100% against death.


In places such as the US some high profiled people are reported to have received the vaccine but then went on to get infected. About 6000 people out of the 140 million who have been vaccinated have been infected but no non has been hospitalized and no one has died. So all these vaccines including the Sinopharm and Sonvac have proven to be effective against severe illness, hospitalization and death. The efficiency against severe complications is very good but they were not designed from getting even the slightest of infection for a day or two.  In short, it is possible to get infected with COVID-19 even after getting vaccinated with any of the vaccines that are being used in the world. However, your chances of getting very ill, hospitalized or dying from COVID-19 infection after getting jabbed are very very very low. Get Vaccinated!











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