Table 2.

Species selection in vaccine specific (A) Repeated dose Toxicity (RDT) studies and (B) Developmental and Reproductive Toxicity (DART) studies of COVID-19 vaccine candidates. Vaccines are anonymized based on their vaccine concept: mRNA(x) (un)modified mRNA-based vaccine encapsulated in lipid nanoparticle (LNP). Adeno(x) = recombinant replication-incompetent adenoviral vector encoding the spike protein antigen of SARS-CoV-2. InAct(x) = inactivated SARS-CoV-2 virus formulated with adjuvant. Sub(x) = subunit: modified spike protein of SARS-CoV-2 formulated with adjuvant.

RDT
Species	Vaccine concept (total nr. of studies)	Age of animals	Number of animals (females + males)
Wister Han Rat	mRNA1 (2)	9 weeks	90
		54/60 days (∼8 weeks)	241
	mRNA3 (1)	9/11 weeks	110
	InAct2 (1)	6/7 weeks	60
Sprague Dawley Rat	mRNA2 (1)	7 weeks	40
New Zealand White Rabbit	Sub1 (2)	12/14 weeks	40
		21 weeks	160
	Sub2 (1)	∼15 weeks	90
	Adeno2 (1)	13/15 weeks	40
CD-1 mouse	Adeno (1)	7/8 weeks	170

DART
Species	Vaccine concept (total nr. of studies)	Age of animals	Number of animals (females only)
Wistar Han Rat	mRNA1 (1)	11 weeks	132
	mRNA3 (1)	7 weeks	60
	InAct2 (1)	(at least) 10 weeks	88
Sprague Dawley Rat	mRNA2 (1)	74 days (∼11 weeks)	88
	Sub2 (2)	(at least 8 weeks)	4 (pilot study)
		6.6 weeks	150
New Zealand White Rabbit	Sub1 (1)	16/19 weeks	132
	Adeno2 (1)	5/6 months	92
CD-1 mouse	Adeno1 (1)	11 weeks	64