TU Delft: Efficiency of 2G and 3G has declined – India Education | Latest Education News | World Education News

At the request of the Dutch Ministry of Health, Welfare and Sport, researchers from TU Delft, UMC Utrecht and Populytics investigated to what extent different types of COVID certificates (coronatoegangsbewijs, CTB) can help prevent the spread of COVID-19 in society. The 3G (vaccinated, recovered, tested) and 2G (vaccinated, recovered) rules are currently much less effective in curbing the spread of the virus than they were two months ago. A 1G policy (only people who recently tested negative have access) is much more effective. But, even if a 1G policy were to be introduced today, the reproduction number would not fall below 1.0.

The study
The Netherlands implemented a 3G policy in 2021: visitors to certain locations had to present a BTC to prove they had recently tested negative, had recovered from coronavirus or had been vaccinated. Other European countries opted for a 2G policy: only cured or vaccinated people were allowed to enter the sites. A 1G policy has also been mentioned as an option in the public debate. The purpose of this study was to investigate the effectiveness of these types of CTB in preventing the spread of the virus in society. The study included two modeling studies and one behavioral study. The modeling studies focused on: (1) the risk of infection of individuals and the number of hospitalizations among visitors to BTC sites and (2) the effect of BTC policy on the spread of the virus in society. (the reproduction number). The behavioral study was conducted among 3,079 Dutch citizens, 783 of whom were unvaccinated. The study was supported by a group of experts from Erasmus MC, Erasmus University Rotterdam, TU Delft, UMC Utrecht and Radboud University.

Conclusions on the effectiveness of the BTC policy
A BTC policy can reduce the number of infections and hospitalizations among visitors to BTC sites. Introducing a 1G policy has a greater impact on reducing infections and hospitalizations among visitors than introducing a 2G or 3G policy. Although 2G and 3G policies reduce the number of infections and hospitalizations among visitors to CTB sites, this effect has been significantly mitigated by the arrival of the Omicron variant.

In November 2021, the 3G CTB policy brought the reproduction number below 1.0. It was possible to curb the spread of the virus because the less infectious Delta variant was dominant at that time. In January 2022, however, the introduction of 2G and 3G CTB policies would not bring the reproduction number below 1.0 due to the higher infectivity of the Omicron variant.
The effect of 1G on the transmission of COVID-19 in society depends less on the level of immunity of the population than 2G or 3G. This would have a particularly significant effect if 1G applied to many places (and therefore contact times) and if the tests used for entry were of high quality.

The effect of 2G and 3G on the transmission of COVID-19 in society is highly dependent on the level of population immunity. The 2G and 3G options are more effective when there is a large difference in the level of protection against infection between unvaccinated people who do not have CTB on the one hand, and people who have CTB either by a vaccine or by proof of cure. the other. The study found that the efficiency of 2G and 3G increases when the policy is used in multiple locations. 2G and 3G are more effective when a larger group of unvaccinated people have not yet had COVID-19. Potential frauds involving COVID certificates and test quality have a much more limited impact on the effectiveness of 2G and 3G.

Omicron
The effect on limiting the spread of the virus in society through a CTB policy has been significantly reduced due to the emergence of the Omicron variant. One of the main explanations for the limited efficacy of 2G and 3G is the reduced protection offered by vaccination against infection with the Omicron variant. In an ideal situation, the introduction of 2G in all places other than schools and at home (e.g. work, restaurants and bars, supermarkets) in January 2022 could lead to a reduction of 16.0 % of reproduction number; for 3G, it would be 15.3%. In an ideal situation, the introduction of 2G in all places other than schools, at home and at work in January 2022 could lead to a 9.8% reduction in the reproduction number; for 3G, it would be 5.4%. The figures above are for the ideal situation, where we assume that 2G and 3G BTC policies have a significant impact on the behavior of unvaccinated people who do not have long-term BTC. However, the behavioral study shows that a large number of unvaccinated people will opt for alternative activities with people other than family members if they no longer have access to certain places. In doing so, they will substitute high infection risk contacts for other high infection risk contacts, which means that 2G and 3G CTB policies will be less effective than in the ideal situation.

The implementation of 1G would be much more efficient. Introducing this policy in all places other than home, school and work would lead to a maximum reduction in the reproduction rate of 19.2%. In the most ideal situation, introducing 1G to all places other than schools and the home would lead to a 44.9% reduction in the number of reproductions. However, even if 1G were to be introduced in all of these places, the reproduction number would still be greater than 1.0.

Conclusions of the behavioral study
A large group of Dutch people who have been vaccinated twice do not know if they should receive the booster. This hesitation is particularly pronounced among young people and among people who went to get vaccinated several months after receiving the invitation. The group of unvaccinated people who say they will get vaccinated if CTB is abolished is larger than the group who say they will get vaccinated if the government introduces 2G or introduces 3G in more places (work/education ). We estimate that around 650,000 unvaccinated adult Dutch citizens visited places requiring a BTC in November 2021. Between 300,000 and 325,000 people did so after testing negative for COVID-19. If this group no longer has access to these places due to the introduction of 2G, around 40% will opt for alternative activities with people other than family members. For example, they may choose to meet at home rather than at a bar. The remaining 60% would not opt ​​for alternative activities or would only choose alternative activities with family members.

Sara H. Byrd