The Key Differences of Pfizer, Moderna and Sinovac COVID-19 Vaccines

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Upon the declaration of the World Health Organization (WHO) of global health crisis due to the COVID-19 on the 31st of January 2020, what came after was a global economic breakdown. And many countries are still in the throes of this economic turmoil. One year after, it’s the new normal. Wearing of mask and face shield is the new fashion, while alcohol is the new cologne.

Many of our fellow Filipinos suffered job loss when the Philippine government imposed the first Community quarantine last March 2020. Not only that, some of us are also forced to reconstruct our daily work lives at home, making people more prone to anxiety, depression, and for an unfortunate few, domestic violence, and harassment. 

But a beacon of light amidst the darkness of the latter year was seen last December 2020 as vaccines, after series of clinical tests are announced to undergo procedures for emergency release and transport around the infected world. However, despite the hope for salvation that they hold some people will tend to ask how do these vaccines work? Will it be safe for us to be inoculated? The report says 94% effectivity, how about the remaining 6%? –Well, it is normal to ask questions because it is our health that is at risk, likewise, it is also right and imperative to answer. Thus here is our take on exploring the medical individualities of some key players that made their appearances in the current vaccine race, Pfizer-BioNTech, Moderna vaccine, China’s CoronaVac (Sinovac), and Oxford’s Astrazeneca.  

The Vaccine’s immunity labors 

People will ask first, how do these Covid-19 vaccines work? In a nutshell, all four vaccines are aiming at the same bull’s eye; to train a person’s immune response or prime the body’s natural neutralizer to destroy the antigens by recreating and simulating the most common Covid-19 conduct of infecting the host body. However, the four vaccines used three different methodologies to perform the intended immunity response training. Both American pharmaceutical giants Pfizer (in partnership with Germany’s BioNTech) and Moderna explored the efficient immunizing tendencies of using messenger RNA (ribonucleic acid), an RNA that contains the genetic make-up of a virus or in layman term, it is simply the virus’ distinctive physique and behavior. The mRNA for COVID-19 would give our body a harmless piece of instruction to recreate a doppelgänger of the virus’ protein spikes – COVID-19’s spikes are the primary penetrating tool of the virus, hence if the body already recognized these spikes as foreign and unknown to our immunity system will create antibodies preparing the body before actual natural infection. mRNA vaccine is advantageous because people injected with these vaccines will have direct protection without having the risk of being or getting ill due to COVID-19. 

Sinovac or CoronaVac, on the other hand, used inactivated or weaken versions of the actual virus. The same strategy is used in creating anti-rabies, chickenpox, and flu vaccines. Attenuated vaccines are modified or treated to make the virus unable to penetrate or invade cells and cause someone to fall ill. After injection, this virus presents itself and shall trigger an immune response. Though, the challenging part of this type of vaccine is that COVID-19 mutates overtime thus a new set of vaccines must be created because experts should capture and make a precise and accurate modification to allow the vaccine to kindle a robust response to protect the body. 

Lastly, Oxford’s AstraZeneca vaccine employs a viral vector strategy to inoculate. It may seem to be similar to the first two in terms of alarming the body of pathogenic invaders, but a viral vector is an injected harmless virus delivering a genetic code from a pathogen and imitate an infection that allows the body to respond against it, therefore training body to fight off the virus before infection. AstraZeneca vaccine used an adenoviral common cold vector from chimpanzees, ChAdOx1 to instruct our body to recreate COVID’s spikes protein. It cannot cause COVID-19 infection for it does not carry enough material to infect like one, but only carry the instruction to assemble a spike protein. 

All four cannot alter a person’s DNA or genetic make-up nor become part of it, so there are no scientific evidence and possibility that we will turn into ZOMBIES after vaccination. 

Reports says Pfizer is effective at 95%, Moderna at 94%, AztraZeneca at 60%, and Sinovac at 50.4%

Reactogenicity: Side Effects at play

Our genetic individuality will play alongside the works of the vaccines. Studies show that unlike most vaccines for other diseases, those formed for COVID-19 are reactogenic, meaning; these vaccines may result in series of unknown physical reactions. Centers for Disease Control and Prevention explained that these reactions are common because they are signs that the body is building up immunity response against the virus and not an account that the vaccine is unsafe. Both Pfizer’s and Moderna’s report that their vaccine may cause pain and redness around the injection spot, fatigue, headache and chills, and muscle pain. People must also anticipate that these reactions will mostly take place after the second shot.  

Sinovac, even with the lowest efficacy rate among the four, has reported no adverse side effects after vaccination. Like Pfizer and Moderna, people shall expect pain, fatigue headaches, and fever. AstraZeneca vaccine also reported these common effects of fatigue, fever, and chills. 

The four-vaccine target to inoculate with 2 doses, 1 per almost or a month apart to people ages 16-18 years and older 

You may have some doubts to vaccinate because of anti-vaccine conspiracies and being injected with one may result in adverse effect for people with underlying illness, however, as far as testing and trials are a concern, the vaccines are perfectly fine and are needed to protect and put us a bit back to our normal lives. 

Cost and Storage and Transport 

Another major concern, of course, is the country’s ability to procure, store and transport vaccines to its people. Thus, varying demands on storing temperature and requirements and prices are a massive issue for underdeveloped and developing countries like the Philippines.

 Looking into these variables it can be noted that Pfizer-BioNtech requires that their vaccine may be stored and transported at negative 75 degrees Celsius and has a life span of five days when stored in regular refrigerator temperature of 2-8 Degrees Celsius, but due to the Philippine’s limitation in storage equipment, there will be the large impossibility of the vaccine being rolled out in the entire archipelago. 

Moderna conversely can be stored and transported at negative 20 degrees Celsius, life span is at 30 days when stored in 2-8 degrees Celsius.

AstraZeneca just needs to be refrigerated with the standard temperature of 2-8 degrees Celsius, likewise, China’s CoronaVac (SinoVac).  

Prices for each vaccine varies from Php. 600 – 5,000. 00 with AstraZeneca with the lowest at Php.610.00, Pfizer; Php. 2,379.00, Sinovac; Php. 3,629 and Moderna price is Php. 3,904- 4,504.00 

The latter explained features of COVID-19 vaccines play an important role in the government’s decision-making, but since, the Government has been preparing and waiting for this since it was first reported, it is expected that the National; together with the Local government shall formulate a systematic plan to give its people the best option to combat the pandemic, to put forward the best interest of their constituents over and against their egos and agenda. 


The emergence of the virus last year has taught us many things; that nature is beyond and greater than us, and some people can be greedy and selfish for survival, but it also made us see the good in some people’s heart, the sacrifices of our frontliners who left their personal lives behind to serve, selfless acts of those who have enough and none, and our innovative characteristics to cope with the changing environment and our continuous belief that someday the sun will shine again. Hopefully, when it does, we will appreciate and take care of it more. 

Let us continue to pray that these developing vaccines are our second chance to be better than before. For in any way that one may be given to us, in any method and requirement that a vaccine may demand, one thing is sure. There is light at the end of the dark tunnel, there is life at the end COVID. 

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