Thought of the Day - February 11 - Worrying Signs

As you know there are only three broad ways to end this pandemic. 1) Stop COVID community infections, 2) Find an extremely effective preventive or therapeutic for COVID-19, or 3) Reach "Herd Immunity" and eliminate SARS-CoV-2. While some countries have been able to achieve the first, this seems highly unlikely for Canada as a whole. After a year of research, there has been no success in achieving the second. So that leaves striving for "Herd Immunity". For some time now I have been looking for evidence that somewhere in the world has managed to achieve this as an indicator this is possible.

Unfortunately, things are not looking good. Given the infectivity of SARS-CoV-2, it was expected that "herd immunity" effects would start to be seen when over 65% of the population was infected, but now the percentage-required quoted by experts keeps going up.

1) As already reported, Israel has vaccinated over 60% of its population, and with close to 10% of the country already infected, they should already see the effect.

But unfortunately, to date, there has been minimal reduction in new cases, indeed lockdown measures have recently been extended.

2) Manaus, in Brazil, has been one of the worst-hit areas in the world. Serological studies had indicated that 76% of the population had been infected by late last year, and yet they have seen a major flare-up in January.

(the second graph is the rate if spread >1 the number of infected people is decreasing, >1 exponential growth)

3) In South Africa, there is growing evidence that their variant (501Y.V2) is reinfecting some people who had COVID-19 before. Last Sunday, the country even stopped its rollout of the AstraZeneca vaccine after data came to light suggesting that the vaccine does not protect against mild or moderate disease from the new variant. In response, AstraZeneca announced they will have a new vaccine ready for use by the autumn. In addition, the Johnson & Johnson and Novavax vaccines, which were trialed in parallel in multiple countries, also seem less effective in South Africa—falling from 72 to 57 percent efficacy and 89 to 49 percent efficacy, respectively.

4) Over half the countries in the world have not started any kind of vaccination program to try to accelerate the achievement of herd immunity. While for many this is more an economic and logistics issue, for others, it is also driven by prudence, the need to confirm that the vaccines are safe and effective, but also that immunity can be achieved.

So while it is just conjecture, this could this mean:

• that "Herd Immunity" is only reached when the vast majority (85-90%+?) of the population is exposed (naturally or via vaccine);

• that immunity does not equal reduction in the ability to spread, just a reduction in the severity of the disease;

• the characteristics of the new 501 variants (UK, SA, and BR) have changed the game;

• so-called "immunity" just wears off.

Regardless of the driver, we are starting to get indications that "Herd Immunity" will be very hard to achieve, if possible at all.

Cheers

Cliff