Israel data confirms that vaccine cannot prevent a COVID case surge
Israel COVID data suggest that vaccines cannot prevent an upcoming COVID surge. The vaccine did not prevent any of the previous COVID surges such as Alpha, Delta, and Omicron variants. Vaccine effectiveness increased when fewer COVID cases were reported. However, vaccine effectiveness was near zero, zero, or negative when a COVID surge was developing. Therefore, we must need some other effective measures when a surge is in effect.
One of the struggles we face to evaluate vaccine effectiveness is data analysis. There are complexities and uncertainties in those analyses for various reasons. Therefore, here I found a reasonably good qualitative argument while not adding too much data processing through different modeling and assumptions. This may not be perfect. However, we can get useful information and learn the dynamics.
Israel collected weekly COVID case data by vaccination and age group. They further broke down to different vaccine groups such as ‘positive 1 to 6 days after 1st dose’, ‘positive 7-13 days after 1st dose’, ‘positive 14 to 20 days after 1st dose’, ‘positive above 20 days after 1st dose’, ‘positive 1 to 6 days after 2nd dose’, ‘positive 7 to 13 days after 2nd dose’, ‘positive 14 to 30 days after 2nd dose’, ‘positive 31 to 90 days after 2nd dose’, ‘positive above 3 months after 2nd before 3rd dose’, ‘positive 1 to 6 days after 3rd dose’, ‘positive 7 to 13 days after 3rd dose’, ‘positive 14 to 30 days after 3rd dose’, ‘positive 31 90 days after 3rd dose’, ‘positive above 90 days after 3rd dose’, and ‘positive without vaccination’. The age group they broke down as the following- over 90, 80-89, 70-79, 60-69, 50-59, 40-49, 30-39, 20-29, 0-19 years old. Israel also documented the same age and dose specific vaccination data.
As COVID infection varies depending on the age group, it can be useful to compare the vaccinated case percentage of all cases with the vaccinated population percentage of all populations for the same age group. This can show qualitative information on vaccine effectiveness and overall dynamics. If both percentages are the same, vaccine effectiveness (VE) is zero. If the vaccinated case percentage is higher than the vaccinated population percentage, VE is negative. If the vaccinated case percentage is lower than the vaccinated population percentage, VE is positive.
The following figure can be helpful to understand different populations for each age group. For example, if we compare one dose (at least) vaccinated case percentage with one dose (at least) vaccinated population percentage, we can consider total cases and total population for a given age group in the denominator respectively. However, if we compare the 3rd dose (at least) vaccinated case percentage with the 3rd dose (at least) vaccinated population percentage, we have to subtract all the cases and population for those groups who received only one or only two-dose vaccination. There is still the possibility of misguidance due to Simpson’s paradox (if I understand the definition of this paradox correctly). However, for a narrow age group (considering that the infection rate is equal for each one in that age group) and equal probability of vaccination for each person in that age group, the error is greatly minimized.
Let’s first check vaccination (at least one dose) effect for age group from 80-89, 70-79, 60-69, 50-59, 40-49, and 30-39. Here, vaccination data were picked at the beginning of the week (say 2020-12-20) while case data were accumulated at the end of the week (2020-12-26). We can make a few interesting observations from the figure below. During a case surge (Alpha, Delta, and Omicron), the vaccinated (at least one dose) case percentage is almost equal to the vaccinated (at least one dose) population percentage. Please note that the axis (for the immediate figure below) for weekly reported case data is the same for all age groups so that we can see which age group might have played a significant role in virus spreading.
Now, let’s focus on only one dose vaccinated case percentage and only one dose vaccinated population percentage. For the first three weeks, most of the age groups (except 70-79 years old) reported a higher number of COVID cases compared to unvaccinated people. Therefore, during last winter (Alpha) surge, partially vaccinated people drove the COVID cases. This is also evident from other studies. In this video, I have shown the same outcome previously based on a study published in Nature. However, it is interesting to notice that during the Delta surge, the one-dose-only vaccinated group showed a significantly lower case percentage. During Omicron surge, one dose only vaccinated group showed almost same case ratio as unvaccinated people for 80-89, 70-79, and 60-69 age group while case percentage among one dose only vaccinated people is relatively lower for 50-59, 40-49 and 30-39 year age group.
Comparing the two-dose-only-vaccinated case percentage and the two-dose-only-population percentage, we can see a somewhat opposing picture. During the Alpha (last winter) surge, double-dosed vaccinated cases were lower than unvaccinated cases. However, during delta surge (last summer) double dosed vaccinated cases were higher or equal for all age groups (except 30-39 years old). This opposing dynamics (1st dose vs 2nd dose) is interesting and it demands to figure out why. Nonetheless, both surges are driven by vaccination. When the virus spreads, unvaccinated people are likely to get infected and therefore case numbers among unvaccinated people are supposed to go up as well.
For the third dose (at least), we can again see that vaccinated cases increased during the Omicron surge. On week 54 (when Israel began its 4th dose vaccine campaign), vaccinated (at least 3 doses) case percentage and vaccinated population percentage became almost equal for all age groups. Since then vaccinated case percentage was dropping somewhat. Vaccinated case percentage again started to rise since week 56 for 50-59, 40-49, and 30-39 age group even though overall cases were dropping. As of 2/7/2022 (week 60), the rate of 4th dose vaccination was 27.9% for 60-69 yrs old and above 45% for above 70 years old age group. The younger age group did not receive 4th dose vaccines.
It is very clear that vaccine helps reduce cases when there is no surge or when fewer cases are reported. However, the vaccine does not prevent a case surge because during a case surge rate of vaccinated cases is either higher or equal to the rate of unvaccinated cases. When the vaccinated case rate is higher than the unvaccinated case rate, it is a likely scenario that the vaccine helps in driving cases. It could be possible that vaccine helps drive cases all the time, however it provides protection to the vaccinated people during no surge or when fewer cases are reported. If this is the case, unvaccinated people are the most sufferer because of mass vaccination.