Page 13 - IJPS-11-5

International Journal of
Population Studies Human behaviors during the COVID-19 pandemic

A B

Figure 4. The power of air ventilation systems. (A) Open window and (B) mechanical ventilation infection rates. Image obtained from Busato and
Cavallini (2023).

6.2.2. Protection from COVID-positive individuals modern air travel compared to historical troop ship
movements. Shiraef et al. (2022) found no evidence in
At the peak of the early 2022 Omicron surge, including
asymptomatic cases, roughly 4% of the US population was favor of international border closures except in a few
infected. If you walked passed people on a street or were highly isolated countries, for example, New Zealand,
with a group of people, the likelihood of at least one of Australia, and South Korea. Typically, attempting to close
them being infected is shown in Table 3. the borders only delayed the COVID-19 spread by a few
days. Sometimes, partial closures had little effect. For
The risk of infection in an air-conditioned space example, when Trump closed the borders to China, he let
was demonstrated by Lu et al. (2020) in a restaurant in infected Americans return home.
Guangzhou, China, as shown in Figure 5. Among the
83 individuals in the restaurant, 10 were infected with Airplanes were quickly recognized as high-risk
COVID-19. The attack rate to those seated near the index environments for COVID-19 transmission, leading to a
case was ~23%. Small droplet aerosol transmission was sharp decline in air travel. According to TSA passenger
implicated as viral spread occurred beyond six feet. data, and after adjusting for population increases since
2019, US air travel per capita did not return to pre-
Given how easily it is to be infected through aerosol pandemic (2019) levels until 2024. The 2023 population
spray, it is evident why so many people got infected. There level adjusted traffic levels would have exceeded 2019
are actions one can take to reduce the chances of infection, levels if people had followed the traditional Thanksgiving
but unfortunately, each has negative consequences. Table 4 and Christmas heavy traffic patterns. However, the winter
summarizes the NPIs that were employed to avoid infection. surge kept them home.
Other, less impactful forms of reducing the chance of
infection were smart elevators, improved refuse shoots, 6.2.2.2. Testing and contact testing
spittoons, and virus-blocking textiles and fibers. Given that 60% of COVID-19 spread happens from
asymptomatic infected people, the only way to be sure that
6.2.2.1. Border closures someone does not have COVID-19 is to test them. While
During 2020–2021, nearly every country in the world many next-generation tests are under development, the two
imposed border restrictions to curb the spread of SARS- personal pandemic testing workhorses were the polymerase
CoV-2. More than 1,000 new international border closures chain reaction (PCR) and the rapid antigen tests. The
were introduced in 2020 and 2021. As shown in Figure 6 third type of test, antibody, is used to see if someone was
(African Center for Strategy Studies, 2020), it took the previously infected with COVID-19. Notably, only slightly
Spanish Flu 18 months to infect the world, mainly through more than 40% of the people who tested positive for prior
World War I troop ships. infection were aware that they had been infected.
Even with the border closures, COVID-19 spread PCR is a laboratory technique that detects and amplifies
globally within 3 months—highlighting the speed of specific genetic sequences, such as those in viruses and

Volume 11 Issue 5 (2025) 7 https://doi.org/10.36922/IJPS025110040