Which of the following vaccines is contraindicated during pregnancy due to the potential for viral transmission to the fetus?

The vaccine that is contraindicated during pregnancy due to the potential for viral transmission to the fetus is the measles vaccine. This is because the measles vaccine is a live attenuated vaccine, which means it contains a weakened form of the virus. If administered during pregnancy, there is a risk that the weakened virus could theoretically affect the developing fetus, leading to potential birth defects or other complications.

In contrast, the influenza vaccine is recommended during pregnancy, as it is crucial for protecting both the mother and the fetus from severe illness. The tetanus vaccine is also safe and is often given during pregnancy as part of routine prenatal care to help protect the newborn from tetanus. The COVID-19 vaccine, while relatively new, has shown to be safe for pregnant individuals and is also recommended to protect against serious illness associated with the virus.

Therefore, the measles vaccine's classification as a live vaccine makes it the one that poses a risk during pregnancy, which is why it is contraindicated.