There are typically 3-4 phases of testing for vaccines.

Phase 1: Small groups of people (20 to 100) receive the trial vaccine. This phase gathers information on the vaccine’s safety, identifies side effects, and studies how well the vaccine works to cause an immune response.

Phase 2: The clinical trial expands to hundreds (100-300) of trial participants who have characteristics (such as age and physical health) similar to those for whom the vaccine is intended.

Phase 3: The vaccine is given to thousands of people and tested for efficacy and safety.

Phase 4 (if applicable): Ongoing studies after approval, designed to monitor the effectiveness of the approved vaccine and detect any side effects not identified in the clinical trial.

The Emergency Authorization from the FDA allows the use of unapproved drugs in the case of emergencies. the 4 vaccines to be used starting in late 2020 before Phase 1/2 trials were complete for Moderna and before Phase 3 trials were complete for Pfizer/Biontech, Astrazeneca, and Johnson&Johnson.

Phase 3 trials would be completed in late 2022, by which time many covid restrictions and mandates were already dropped and a majority of many populations had already been vaccinated by the time the normal required testing was completed.

https://www.gao.gov/assets/gao-21-319.pdf (Figure 8)

https://www.fda.gov/media/144636/download

I can't argue against the idea that we were in a situation where we needed something fast so decisive action needed to be taken, but we can see some of the effects of the fast tracking. First, the AstraZeneca vaccine (which I don't think was accepted under the Emergency Authorization in the US) was found to have a higher risk of blood clots than the others (Phase 3 testing of that particular vaccine lasted until early 2023) so was restricted for use in places like England and Canada where it was accepted for use. As well, because testing was fast tracked, politicians were out there making false claims about the effectiveness of the vaccines. If the vaccines were really as highly effective as touted, then covid should have gone extinct in populations that were fully vaccinated, but that didn't happen (and the counterpoint to that was that the virus mutated and so the vaccine wasn't for those viruses, but it doesn't particularly matter -- if it doesn't prevent covid it doesn't prevent covid). As well, because of the limited data set due to fast tracked testing, it wasn't known until later that boosters would be required to maintain efficacy after a certain point.

https://www.gov.uk/government/publications/use-of-the-astrazeneca-covid-19-vaccine-jcvi-statement-7-may-2021/use-of-the-astrazeneca-covid-19-azd1222-vaccine-updated-jcvi-statement-7-may-2021

In the United States, the Johnson&Johnson vaccine was first accepted under the emergency use authorization, but later had its use restricted, and then later fully revoked as it became obvious there were potential issues with blood clots:

https://www.cnn.com/2022/05/05/health/fda-johnson-johnson-vaccine-eua/index.html

https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-limits-use-janssen-covid-19-vaccine-certain-individuals

https://www.cnn.com/2023/05/15/health/johnson-johnson-covid-vaccine-end/index.html

https://www.cdc.gov/vaccines/covid-19/info-by-product/janssen/index.html

The US government and the CDC was recommending that pregnant women get the vaccine in April of 2021, over a year before phase 3 testing was completed. That really set off alarm bells for me because typically pregnant women are excluded from medical trials because of the ethical implications of potentially harming a baby in the womb. Thalidomide is a famous example where a drug was approved (not in America but in many other jurisdictions -- For her role in preventing the approval of thalidomide in the U.S., President John F. Kennedy presented Frances Kelsey with the highest award for civilian federal workers, the Distinguished Federal Civilian Service medal.) and it turned out to have unexpected side-effects on unborn children. Given all this, that was a potential risk and I think a lot of pregnant women didn't have the facts required to make a good decision.

https://www.youtube.com/watch?v=kbdoXen3AR8

https://www.fda.gov/drugs/development-resources/division-pediatric-and-maternal-health-clinical-trials-pregnant-women

https://www.reuters.com/article/us-health-coronavirus-vaccines-pregnancy-idUSKCN24W1NZ

At the end of the day, while COVID vaccine skeptics predicted absolutely genocidal consequences for rushing the development of the vaccines, the reality is that the risks paid off. There are some side effects from the vaccines no doubt, but overall we were able to get society back on track significantly before the standard testing regime was completed. The only thing for me is that the government was not being honest to the people about the fact that it was a risk. In my case, I took the vaccine knowing there was a risk because I had a duty to my family to keep my workplace going so I could continue to support them, but some people took it without being properly informed as to the potential risks or the fact that the vaccines were operating under an emergency authorization and testing was not completed.