The Johnson & Johnson (J&J) COVID-19 vaccine was first tested in rhesus macaques, and later in Syrian golden hamsters. The details of both studies have been published in the science journal Nature.

In the first trial, 32 primates received a single dose of the viral vector-based vaccine and 20 received a placebo. Viral vector vaccines use a modified version of a harmless virus to activate the immune system and trigger our immune systems to fight against a harmful virus, such as COVID-19. After four weeks, all vaccinated macaques demonstrated immune responses. After 6 weeks, when exposed to the original strain of COVID-19 or the B.1351 variant, 5 out of every 6 vaccinated monkeys were completely protected against both forms of the virus.

The researchers concluded that a single dose of the vaccine was effective at providing complete or near-complete immunity in rhesus macaques. 

In the second trial, 50 hamsters received a single dose of the vaccine and 10 received a placebo. After 4 weeks, the hamsters were exposed to a high dose of COVID-19. The researchers found that vaccinated hamsters lost less weight and had less virus in their lungs and other organs compared to hamsters that received a placebo. There was no mortality among vaccinated hamsters, while some of the unvaccinated hamsters died. This study demonstrated that a single dose of the Johnson & Johnson vaccine protected the hamsters against severe clinical disease and death after being exposed to a high dose of coronavirus.

Before vaccines can be administered to humans in clinical trials, researchers are required by the Food and Drug Administration (FDA) to conduct pre-clinical trials in animals. 

Though the urgent need for a COVID-19 vaccine has expedited vaccine trials with less animal testing than is typical, all COVID-19 vaccines that have been granted Emergency Use Authorization have undergone animal testing for safety and efficacy. 

A social media post that claimed COVID-19 vaccine manufacturers “skipped all animal trials because all animals were dying” referenced a Texas State Senate hearing that took place on May 6, 2021. A topic discussed was Bill 1669, which seeks to prohibit discrimination regarding vaccination status. From the 44:23 - 45:30 mark of the recorded hearing, Texas State Senator Bob Hall stated that animal trials were skipped due to the animals dying, and pediatrician Dr. Angelina Farella agreed. 

These claims are false. All COVID-19 vaccine manufacturers ran animal trials and none resulted in significant safety issues. While Moderna and Pfizer received FDA approval to conduct animal tests and early human trials simultaneously, this does not mean that animal trials were skipped or shortened.