Effectiveness Over Time & Delta

January 31, 2021

Here again my weekly SARS-CoV-2 update. There have been approximately 103 million official SARS-CoV-2 infections and 2,231,000 official deaths recorded worldwide to date. 94 million doses of vaccine have been administered.

The review will be a bit shorter today, there is a lot of news concerning vaccines.

Cases Trending Downward in Europe

Most countries in Europe are seeing a cases trending downward or stagnating, often at a high level and sometimes despite lockdowns. The main exceptions are Portugal and Spain, which are currently experiencing strong increases in cases. Canada, and finally also the US, see a downward trend in cases, too. In Latin America, the situation is mixed. Colombia and Argentina are coming down from a wave, elsewhere cases are up, and Mexico and Brazil have dramatically more cases. Asia and Africa haven’t changed much compared to last week.

So, now about the vaccines:

AstraZeneca

The AstraZeneca vaccine was approved in the EU. This is very positive for now. Based on published data, we know that it works. It is unclear how well. The efficacy in Brazil was 62%, in the UK 90%. In addition, there is little data for older people.

The reported 8% efficacy in elderly people is not true, there is simply not enough data to make a statement. But based on the immune responses in older people, one can very well assume that the vaccine is also effective in this age group.

My honest recommendation, if you have a choice: Take the Moderna or the Pfizer vaccine, they simply work better. If there is only AstraZeneca vaccine, I would recommend to get vaccinated with it. It is much better than not being vaccinated.

Novavax

So, then Novavax has released initial data (via press release) from their Phase III trial in the UK and a Phase IIb trial in South Africa. Novavax has developed a vaccine based on a recombinant version of the surface protein of SARS-CoV-2, administered with an adjuvant (saponin, derived from a tree).

The vaccine is therefore based on a rather classical technology that is also used for other vaccines that are already on the market. I also assume that this vaccine – after appropriate safety studies – will be approved for use in children and adolescents. The EU currently has no contracts with Novavax.

In the UK, the efficiency was 89%, which is very good. Then they also looked at how well the vaccine works against the “normal’ virus” (we call that wild type) and the British variant (B.1.1.7). Against the wild type virus, the efficiency was 95.6%, against the B1.1.7 variant the efficiency was 85.6%. This means in principle that the vaccine works well against both variants, especially if you look at the confidence intervals (uncertainty), there are probably no serious differences.

The data from South Africa are also interesting. However, that was a phase II study and the number of cases is small, and the data are therefore much less robust. In South Africa, the efficiency was much lower, at 60%. Most of the cases were caused by the South African variant (B.1.351). If we consider only cases with this variant, the efficiency is about 50%. I will discuss this further below.

Johnson & Johnson

Johnson & Johnson (J&J) has also announced initial data (and also via press release) from their Phase III trials in the US, Latin America and South Africa. The vaccine is a viral vector vaccine based on an adenovirus 26 (also a component in the Russian Sputnik V vaccine, the same vector already used in an approved vaccine for Ebola in the EU). The peculiarity here is that the vaccine is given in a one-jab regimen. A second phase III trial in which the vaccine is given two times was also started, but later, and there are no results yet. The EU has ordered 200 million doses of this vaccine.

Vaccine efficacy (measured as reduction of moderate and severe COVID-19 cases – this is different from other vaccines where mild cases were also included) was 72% in the U.S., 66% in Latin America, and 57% in South Africa. As with Novavax, one assumes that the lower efficiency in South Africa can be explained by the variants there.

They also looked at the efficiency against severe cases in particular, which was 85% over the whole observation period and 100% when one started counting 49 days after vaccination (unclear why the effect improves later).

The clear advantages of vaccination: few vaccine reactions, can be stored at 4°C, and only needs to be given once. The clear disadvantage: lower efficiency.

Virus Variants

We now have three variants that cause problems: The “British” variant B.1.1.7, the “South African” variant (B.1.352), and the “Brazilian” variant P.1.

While these variants were discovered in their respective countries, they are not named after those countries and one should use the official names. All three variants are slightly more infectious than the “wild-type” virus and therefore spread slightly faster. Based on current data, the variants are no more dangerous than the wild type.

• The B.1.1.7 variant is well neutralized by antibodies of vaccinated persons – and there is now good data in the laboratory but also from the Novavax study – so it is not a major problem as far as vaccinations are concerned.

• The B.1.351 variant is still neutralized, but less well (tested with the Pfizer and Moderna vaccines). Therefore, there may be a reduction in the efficiency of the vaccines. This does not mean that they are not effective. And even if diseases should occur in vaccinated persons with these variants, the disease is strongly attenuated by the already existing immune response and a high protection against severe diseases is to be expected also against this variant (which is partly already seen in the J&J study).
  
• The P.1 variant is very similar to the B.1.351 variant. While there is still little data on the P.1 variant, it can be assumed that it behaves like B.1.351. So, still no reason to panic. Strategies to quickly readjust vaccines regarding variants are being worked on to be able to act if necessary. By the way, it is amazing that these variants have emerged quite quickly. I honestly expected a slower virus evolution.

So, now an update on my vaccination. I received the second Pfizer mRNA partial vaccination on Tuesday last week. About 7 hours later, my arm started to hurt slightly. 24 hours later, the pain went away. And I had a slight redness of the skin near the injection site, which also went away within 2 days. That was it. It was quite unproblematic, at least for me.