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COVID-19 is an ongoing pandemic and the information will be updated as we know more

(last update 14 June 2021)

The COVID-19 has claimed more than 1.8 millions lives worldwide in 2020 alone. This is our generation's "Spanish Flu" which took over 50 million lives (or 2.5% of the world population). If we extrapolate to our 7.8 billion world population this translates to a potential 200 million dead if left unchecked and without modern medical treatment / vaccines. I remember being told repeatedly in the 1990's as a medical student by my lecturers that the something like the "Spanish Flu" will return every 100 years. 

There are only 2 ways back to "normal" 1. "mass vaccination" 2. "natural immunity". Option 2 will mean an estimated 200 million dead if we used the Spanish Flu as a guide and this is how nature works. We are the fortunate descendants of people who did not die from the past epidemics such as the Spanish Flu; Bubonic Plaque; Small Pox and more. 

There are a few major vaccines which have been approved and had completed phase III clinical trials. There are a few misconceptions about vaccines and a ton of fake news. These are the facts on vaccines in general 

1. Vaccines do not prevent infection - they work by allowing a mild form of the infection to take place instead


The first documented vaccine was the Chinese vaccine for smallpox in the 15th Century (A History of Immunology Arthur M. Silverstein 2009). In 1796 Edward Jenner used pus from cowpox to vaccinate against smallpox after his observation that milkmaids who were exposed to cowpox; rarely suffered from the severe form of smallpox. These original vaccines allow only a mild form of the infection to occur and most modern vaccines do the same.

2. Vaccines do not eliminate transmission but reduces greatly the risk of transmission


This was seen before in vaccinated children with chicken pox (varicella zoster) and other common viral infections. At present the infectivity of persons vaccinated but exposed later to COVID-19 is not known but the assumption is that it may be reduced but not eliminated. Early data suggests reduced viral load in vaccinated subjects with the implication that it will reduce transmission. Proving reduction in transmission is hard as most countries will have implemented other policies that reduce transmission e.g. masking and social distancing. Of course any reduction in viral load and transmission should help towards "herd immunity". 

3. Vaccines were not rushed


The greatest delay in vaccine development is getting funding and recruitment of test subjects. 


Funding was not an issue with COVID-19 as the scale of the pandemic meant that governments were ready to commit large amounts of funding in view of the devastating effect on the economy. Massive funding was made available for the development of many different types of vaccines simultaneously. 

Recruitment was not an issue in some countries as the numbers infected rose exponentially. The basic science for the mRNA vaccine was already established in the early 2000's and viral vector vaccines were already rolled out for Ebola virus in 2019.

Diseases which progress slowly will also take a long time to conduct; for example heart attack studies may take many years to show benefit as the second heart attack may come many years after a patient takes part in a study. Since severe COVID-19 infection will usually ​manifest within weeks of the infection and in addition, we saw hundreds of thousands infected daily, event rates are accrued rapidly and the study had enough data to run statistical analysis in a short period of time. 

4. Vaccines are extremely safe


COVID-19 vaccines are extremely safe and more than 20 million adults in the UK have been vaccinated by Mar 2021.


There have been case reports on heart attacks or even deaths after vaccination. But we know that correlation is not causation. The phenomena of heart attacks (or some other event) after a vaccine is given is seen when a country vaccinates large numbers of her elderly and vulnerable population. Because we have more than 10 heart attacks per day in Singapore affecting the elderly (> 70 year old); it stands to reason that statistically some of these heart attacks will happen the day before or after vaccination; will one still blame the vaccine if a heart attack happens the day before the vaccine ?


To prove that vaccines lead to more heart attacks, we should expect more heart attacks a month in Singapore in 2021 as large numbers of elderly were vaccinated in the first quarter of 2021. MOH and all public hospitals in Singapore tracks our heart attack rates closely and we will know very quickly if there is a real increase in heart attacks after we start our vaccination program. 

Other side effects such as Bell's palsy and clotting disorders do occur and present randomly with or without COVID-19 vaccines and the only way to demonstrate cause and effect is to see if the number of such cases at a national level are above average during the vaccination program. Anecdotal cases reported in mass media or social media are not evidence of cause and effect but may perhaps form a basis for tracking these events closely. 

Myocarditis and mRNA vaccines (update 14 June 2021)

US FDA and CDC released data from their VAERS which suggests that there is an increase risk of myocarditis with the mRNA vaccines currently approved for use by US FDA (Moderna mRNA-1273 and Pfizer-BioNTech BNT162b2 vaccines). This risk is about 2.3 in 100, 000 subjects in those aged 12 - 24 yrs old compared to a 0.2 in 100, 000 subjects in those aged 25 and above. As the risk of myocarditis with COVID19 infection is 2300 in 100,000 in the young, the advantage of vaccination far outweighs the risk of contracting COVID19. 

Idiopathic Thrombosis with Adenoviral Vector Vaccines (update 14 June 2021) 

European Medicines Agency released a series of reports on the risk of thrombosis after vaccination with the AstraZeneca AZD 1222 / ChAdOx1 vaccine. The risk appears to be higher in those aged 30 and below. Risk benefit will now shift depending upon the risk of contracting COVID19 in your country vs the risk of thrombosis. 


Number of Heart Attacks remain stable in Singapore over Mar / April / May 2021 (when vaccination started for our elderly population). This crude analysis will pick up large effects and will require continuous monitoring over a longer time period to be conclusive but is nonetheless very reassuring. 


Countries with large uncontrolled outbreaks of COVID-19 in an unvaccinated population in 2020 had much larger number of additional heart attacks and total death. 

Visual risk contextualisation

(23 April 2021)

easy to visualise graphs to see what is your risk of thrombosis vs risk of serious illness from COVID19

Signal Assessment Report

(24 March 2021)

easy to visualise graphs to see what is your risk of thrombosis vs risk of serious illness from COVID19

Natural Herd Immunity for COVID-19 doesn't work

Manaus epidemiological data (link to Lancet) 

Experience from Manaus; Brazil shows that "natural herd immunity" with 76% infected after the first wave only promotes new more deadly and transmissible strains and they saw an even more deadly 2nd wave. 


National Vaccination Programs work

Israel National Vaccination Program (link to NEJM) 

They were able to show large reductions in severe COVID-19 cases by just vaccinating their elderly and vulnerable folks. 

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