Understanding the COVID-19 Vaccines

With 109 million infections and 2.4 million deaths caused by the pandemic, as well as $500 billion lost monthly in the global economy due to COVID-19, multiple vaccines have been developed to protect people against the virus. As of mid-February 2021, 176 million doses of 8 different vaccines have been administered to people in 78 countries. Here’s a brief overview of these new vaccines.

If you want to learn more about COVID-19, we have a guide for that

How vaccines work to fight COVID-19

Vaccines have a simple principle: Introduce a harmless imitation of a pathogen into your body and let your body safely train its immune system against this impostor. Once your body has developed the ability to fight the vaccine, it can use both the antibodies built up as well as the immune memory developed to later fight the actual pathogen.

In the case of COVID-19, there are a number of different vaccine technologies that have been developed and tested for safety and efficacy in record time. Some of them use older approaches such as a “trojan horse” viral vector, others use a “cooking recipe” messenger RNA. Unlike the flu shot, a best-estimate cocktail of vaccines against 3-4 different circulating influenza viruses that cause the infections collectively known as “Flu,” COVID-19 vaccines are specifically attacking the spike protein of the novel Coronavirus currently causing the pandemic.

Each person vaccinated becomes a protective shield for themselves and their community by slowing down the chain of infection. Universal mask-wearing helps protect everyone on top of the vaccine. When  there are enough protectors in a community, the group reaches “herd immunity” and the virus cannot replicate or spread as readily. This is when an infectious disease is declared eliminated in a geographic area, as has been accomplished with Measles, Mumps and Polio. When this elimination reaches a global level, the disease is eradicated, as is the case with Smallpox and Rinderpest. Herd immunity through vaccination is a combination of self-protection and teamwork. Vaccination is the only method through which we have ever reached herd immunity. [WHO]

Side effects and risks of the COVID-19 vaccine

COVID-19 vaccines are new and side effects are still being studied (full list here by the CDC). Side effects are not unique to the COVID-19 vaccine. In fact, they are common across vaccines and are an indication that your body is generating its protective shield. This is your immune system in action. Common side effects for the COVID-19 vaccines include fever, chills or fatigue (similar to when you get a flu shot). In extremely rare cases, some recipients had an allergic reaction to the vaccine.

The U.S. tracks adverse vaccine reactions via the VAERS system, which utilizes a voluntary reporting scheme from Healthcare providers, vaccine manufacturers, and the public. So far, 12,685 adverse events have been tracked (out of which 1,399 required hospitalization) while 52.88 million doses have been administered as of February 14th, 2020 in the United States. [HHS VAERS] [OurWorldInData]

Adverse Reactions to COVID-19 Vaccines, via VAERS (as of 2/14/2021):

Days in HospitalCases
1 day310
2 days228
3 days136
4 days80
5 days56
6 days35
7 days16
8 days10
9 days5
10-14 days24
15-30 days10

Comparing vaccine and disease data, the preliminary findings suggest that a COVID-19 infection is 1,574 times more likely to require hospitalization than complications from the COVID-19 vaccines.

SubstanceEst. Risk of Requiring HospitalizationRisk of Death
COVID-19 (Sars CoV-2)1:24*1:166**
COVID-19 Vaccines  (USA)1:37,798***0:52.8M****
Above figures compare verified vaccine reactions (including unknown outcomes) to projected total COVID-19 infections (including asymptomatic / undetected cases) – rather than confirmed cases – in order to achieve the most conservative estimate. Learn more about CFR / CHR compared to IFR / IHR.

* Average hospitalization length for clinical COVID cases is 10-13 days for survivors (Source: CDC); the estimated average Infection-Hospitalization Rate (IHR)  of COVID-19is 4.2%. Source: UT Austin
** The estimated average Infection-Fatality Rate (IFR) of COVID-19 is 0.6%. Source: Public Health Agency of Sweden
*** 1,399 hospitalizations (VAERS data) on 52.88M vaccine doses in the United States.
**** To date, no deaths have been causally attributed to  the various COVID-19 vaccines in the US or abroad. In other words, neither the  VAERS data nor vaccine trials have detected patterns in cause of death that would indicate a safety problem with COVID-19 vaccines. Reports of adverse events in the VAERS data align with expectations from  vaccine manufacturers; deaths .

As of February 2021, 176 million doses of 8 different types of COVID-19 vaccines have been given to people in 78 countries. The VAERS system has received multiple reports of deaths in close proximity to vaccination (934 total), but no causal relationship has been found by the CDC: “To date, VAERS has not detected patterns in cause of death that would indicate a safety problem with COVID-19 vaccines […] A review of available clinical information including death certificates, autopsy, and medical records findings revealed no link with vaccination.” [CDC]  [WHO] [Reuters] [DW]. 

What happens once you get the vaccine?

Once you have received the vaccine, your body needs about a month to build its antibody regimen in response to the vaccine. If you received a 2-shot regimen, immunity will begin around 1-2 weeks after your second shot. [BMJ] [FDA] What does this mean? Your chance of developing a severe COVID-19 infection is extremely low – that’s the job of the vaccine. You can still get infected with the virus – but your body will be able to deal with it without causing you severe symptoms since it has the proper immunity built up. As of February 2021, it is not known if the vaccine prevents you from being infectious to others.  [CDC]

For this reason, it is likely that your local jurisdiction will require you to keep wearing a mask, practice social distancing, etc. for the coming months after your vaccination – until most people in your community have been vaccinated, so the spread can finally be stopped. [NY Times]

Which vaccines are currently available?

The NYT has put together a handy vaccine tracker that is continually updated. You can filter by trial phases, technology and more – it is a comprehensive COVID-19 vaccine technology tracker  and applies to all 40+ vaccines in development as well as the 8 vaccines approved for early emergency use. Additionally, the WHO has a complete List of COVID-19 vaccines in development in the form of a publicly accessible spreadsheet.

Here’s an overview of the technologies used in these 8 different COVID-19 vaccines:

Viral VectorViral pathogen expressed on a safe virus that doesn’t cause diseaseRapid developmentPrior exposure to vector virus (e.g. adenovirus may reduce immunogenicityAstraZeneca COVID-19, CanSino COVID-19, Ebola
Inactivated VirusInactivated dead virusInduces a strong antibody responseRequires large quantities of virusSinovac COVID-19, Sinopharm COVID-19, Influenza, Rabies, Hepatitis A
RNA and DNADNA or RNA coding for a viral protein, expressed by host cellStrong cellular immunity; rapid developmentRelatively low antibody responseBioNTeach/Pfizer COVID-19, Moderna COVID-19 
Protein SubunitA protein derived from a pathogenMay have fewer side effects than whole virus (less redness, swelling on injection site)May be poorly immunogenic, complex processNovaVax COVID-19, Influenza
Virus-Like Protein (VLP)Virus-resembling protein structuresSafer than inactivated virii, self-adjuvantingSometimes unstable, difficult to purify in productionSerum Institute COVID-19, Hepatitis B, Papillomavirus
Source: WHO, Oct 2020 / Source: Immunology Research Journal, 2018

Bloomberg has also published a vaccine development tracker; it only follows the top 10 candidates, but offers detailed information on approval history.

When can you get the vaccines?

Each country has their own roll-out plan and schedule. Some organizations have published estimated times on when you can get the vaccine based on your risk exposure due to job, age, and other factors. [USA Today]

Generally, most countries have adopted the strategy of vaccinating healthcare workers and the elderly population first, followed by frontline workers, and then followed by the general population, (starting with older people and ending with younger people). This global roll-out is projected to last for a minimum of 18-24 months, with the largest effort promising around 2 billion doses by the end of 2021. [COVAX]

You can follow the global roll-out via the Bloomberg Global Vaccine Distribution Tracker. As of February 2021, 176 million doses have been given in 78 countries.

How were these vaccines developed so quickly?

Vaccine technologies have existed for 100+ years. Even the new mRNA vaccines have a 30-year research history. Parts of the current coronavirus vaccine research work were complete when scientists around the world tried to construct vaccines for SARS and MERS more than a decade ago. These vaccines never made it to market since the population was able to prevent the spread of both of these viruses. [Nature] [NIH]

When COVID-19 began spreading in December 2019, the genome of the virus was quickly mapped by scientists in China, Germany, and other countries independently. Many vaccine manufacturers started research and development work simultaneously. By early 2020, a dozen companies had a prototype vaccine that was developed into the vaccines  available today, with more of them still undergoing the final phases of testing. [Science]

Testing phases were combined and accelerated while maintaining the same safety standards. Government resources were hyper-focused on the development and evaluation of these vaccines – spending more than $39 Billion on vaccine development. The combination of all these factors allowed the largest and most expensive vaccine development effort in human history to move at record speeds. [Nature] [Guardian]

Source: WHO

Are the current vaccines effective against variants?

On February 22, the FDA updated the Emergency Use Authorization for Vaccines to Prevent COVID-19 to provide guidance for current approved vaccine developers to amend their existing EUAs should they need to address emerging variants of the COVID-19 virus and modify their vaccine formulations. 

The current vaccines should offer at least some degree of protection against newly identified variants; however, a preliminary report from the New England Journal of Medicine suggests that some vaccines may not be particularly effective against the B.1.351 variant from South Africa. The CDC recommends that people continue to wear masks, maintain social distance, and avoid crowds even after receiving the second vaccine dose as part of a strategy to help stop the spread of COVID-19.

A look towards the largest vaccination effort in history: COVAX

Multiple large international endeavors are underway to aid vaccine manufacturers and governments in facing the logistical reality of distributing billions of doses within a year across 7 continents.

The largest such effort is COVAX, an effort sponsored by CEPI, GAVI and the WHO, binding 172 signatory countries (80 high-income and 92 low-and-middle-income countries)  around the world to a global agreement on vaccine purchasing and distribution for at least  2 Billion doses by the end of 2021, protecting the world’s most vulnerable 20% within this year. COVAX is the largest multilateral agreement since the Paris Climate Accord.
[Reuters] / [VOX] / [United Nations]

COVAX is the third stage of ACT, the Access to Covid-19 Tools” Accelerator, with  the following strategy:

  1. Diagnostics: Investment Case by the WHO
  2. Treatments: Investment Case by the WHO
  3. Vaccines: Investment Case by the WHO
  4. Strengthened Health Systems (Led by World Bank and Global Fund)    

In summary

  • COVID-19 is the largest pandemic in 100 years, having caused infections in at least 188 countries with 109 million known infections and has caused 2.4 million deaths world-wide as of February 2021. [JHU]
  • $500 billion lost monthly from the global economy due to the pandemic. [COVAX]
  • The current most likely end to the pandemic will come through a vaccine, as has happened before with infectious diseases.
  • Using lessons learned from experimental vaccines against SARS and MERS, dozens of COVID-19 vaccine candidates are in different phases of roll-out and trials. 
  • 8 vaccines are now available through Emergency Use Authorizations in 30+ countries, having been administered to a total of 31+ million people. Another 10 vaccine candidates are in Phase 3 so far, each in the process of testing the vaccine on 30,000+ people. 
  • The world is entering the largest vaccination effort in history. [WHO, Oct 2020]
  • The WHO is also backing COVAX, the largest multilateral agreement since the Paris Climate Agreement with 172 countries signatory to it. COVAX provides a model of equitable distribution internationally, with the motto “No one is safe until everyone is safe”, preventing vaccine nationalism and stockpiling. Through COVAX alone, the goal is to distribute 2 Billion doses by the end of 2021. On behalf of COVAX, UNICEF will stockpile 1 billion syringes for vaccine distribution by 2021. [Reuters]
  • Successful vaccine manufacturers such as Moderna, Pfizer and AstraZeneca have published their 100+ page Phase 3 protocols, a rare move towards transparency.

“No one is safe until everyone is safe”.

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