Pfizer recently announced that its trials in children 2 to 5 years old produced a weaker than expected antibody response and that it would hold off requesting authorization from the Food and Drug Administration. This news creates opportunities – and additional challenges – for off-label use of Covid-19 vaccines in children,

Faced with mandatory Covid vaccination, students and employees have appealed to religion as grounds for exemption. This latest conscience war within our culture wars presents a minefield of legal and philosophical complexities for states and health care systems.

Last month, with concerns over the supply and coordinated administration of coronavirus vaccines escalating, the Centers for Disease Control and Prevention conceded that “any available mRNA COVID-19 vaccine” may be used to complete vaccination in “exceptional situations” preventing multi-dose manufacturer matching. While presented solely as a last resort, this guidance reflects a dilemma currently sweeping across the medical and health policy worlds: given limited supply, should vaccination efforts—still only authorized for emergency use in this country—deviate from evidence-driven, studied regimens to maximize individuals reached?

A third Covid vaccine candidate moving closer to potential FDA authorization is less effective than the two Covid vaccines already authorized in the United States. Is it ethical to offer a vaccine with lower efficacy? Is it ethical not to offer it in a public health emergency?

Suppose you are young, healthy, employed in a health care system and that your line of work does not require leaving the low-risk comfort of your home. Now suppose that your employer offers you a vaccine. You know there are others in your community who are at greater risk of contracting and dying from Covid-19 than you. Should you accept the dose?

A Covid-19 vaccine developed by Pfizer and BioNTech has received emergency authorization in the United States and has been authorized in the countries, and a vaccine by Moderna is likely to be authorized soon. In spite of this good news, at least for the first couple of years, Covid-19 vaccines will be a scarce resource. Because low-income countries are likely to lose out in the scramble to get access to them, there have been calls for global solidarity. While equitable allocation of vaccines around the world would be ideal, it is unrealistic as a near-term goal.

Experts in infectious disease and public health warn that the Covid-19 pandemic will be with us until there is an effective vaccine, possibly 12 to 18 months in the future. This situation has given rise to calls for human challenge studies, in which healthy volunteers are injected with an experimental vaccine and then infected with the disease to test the vaccine’s efficacy. Is this ethically justifiable?