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Opinion: Understanding Covid-19 vaccines

2021-07-08  Staff Reporter

Opinion: Understanding Covid-19 vaccines
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Dr Vetja Haakuria

 

Vaccines have proven to be a potent weapon in our armory against infectious diseases. 

The gains of vaccines include eradication of polio, smallpox and other debilitating diseases afflicting mankind. Currently, Namibians are routinely vaccinated against tetanus, mumps, measles, rubella and countless other infections.

Vaccines for Covid-19 are no different from these routine vaccines that we get at our various clinics and hospitals. 

At the moment, only the Moderna and the Pfizer vaccine are produced using a new technology, the mRNA technology. Oxford/AstraZeneca, Sputnik V and Johnson&Johnson are all recombinant vaccines.  Recombinant technology is an established technology and there are countless vaccines on the market based on it.

The technology clones genes encoding the spike protein of SARS-Cov2 into the Adenovirus (which is harmless to humans).

This virus then produces these spike protein inside mammalian cells (not necessarily human cells eg. CHO cells) which are then purified and formulated into a vaccine. 

However, only Oxford/AstraZeneca vaccine has well-defined blood clot issues, though this is also very rare (eg. four cases out of one million in Norway). This is often a complex mix of both the patient’s innate genetic make-up and the excipients (stabilisers, adjuvants etc) in the formulation. It is like allergies, some patients are allergic to penicillin while others are not for example. 

It is important to remember that the vaccine does not contain genetic material, the vaccine contains the protein from the virus, so no DNA is injected into the patient. Also important to remember that all vaccines have different side-effects including Sinopharm. 

Moderna and Pfizer (mRNA vaccines) have myocarditis and pericarditis issues in some younger people. 

The complexity of the human immune system makes all the difference. 

Sinopharm is a whole virus which is inactivated to weaken it. It is not a killed virus vaccine  though, but a live virus vaccine. The danger with live vaccines is that they revert back to pathogenicity in time. 

But killing the virus can reduce its ability to elicit a strong immune response, making it useless. So those are the challenges with vaccine development. 

To increase the efficacy of vaccines, we sometimes add substances called adjuvants. Adjuvants cause side-effects in some people. 

So you may have a vaccine that gives good protection but cause side-effects in a small portion of patients. In addition to headaches and nausea, Sinopharm causes acute disseminated encephalomylitis (a rare neurological disorder) as well very rarely blood clots too.

So we need to follow scientific developments closely as new information trickles through and make decisions based on sound science. 

While opinions are at times unavoidable, they carry an inherent bias, hence the need to proceed with care in this space. Echoing Dr Bernard Haufiku’s statement, there is no question that vaccines are absolutely critical to controlling SARS-Cov2 transmission and limiting its mortality in humans. Public engagement as championed by professionals like Dr Haufiku is important in enlightening the general public to enable them make informed decisions regarding vaccination.

 

•Dr Vetja Haakuria is vaccine development scientist


2021-07-08  Staff Reporter

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