One problem with vaccines that contain killed pathogens is that
they may not stimulate a strong response.
they may stimulate an excessive immune response.
they can only be given to immunocompromised people.
the pathogen may reactivate and cause disease.
they cannot be given to immunocompromised people.
The correct answer and explanation is :
The correct answer is: they may not stimulate a strong response.
Explanation:
Vaccines made with killed (inactivated) pathogens are designed to expose the immune system to a disease-causing microorganism without the risk of causing the actual disease. However, one main problem with these types of vaccines is that they may not stimulate a strong immune response compared to vaccines made with live, attenuated (weakened) pathogens.
When a pathogen is killed, its ability to replicate inside the body is completely eliminated. This is good for safety, especially in people with weakened immune systems, but it also means the pathogen does not multiply and continuously present antigens (substances that trigger an immune response) to the immune system. As a result, the immune system sometimes does not recognize the vaccine as a significant threat, leading to a weaker or shorter-lived immune response.
Because of this weaker stimulation, inactivated vaccines often require multiple doses (boosters) to achieve and maintain immunity. Examples of killed pathogen vaccines include the polio (Salk) vaccine, hepatitis A vaccine, and the rabies vaccine.
Let’s quickly rule out the other options:
- They may stimulate an excessive immune response: Not typically. Killed vaccines usually create a weaker, not stronger, immune response.
- They can only be given to immunocompromised people: Incorrect. They are safe for immunocompromised individuals because the pathogen is dead and cannot cause disease.
- The pathogen may reactivate and cause disease: False. Since the pathogen is killed, it cannot reactivate.
- They cannot be given to immunocompromised people: Also incorrect. Killed vaccines are specifically safer for immunocompromised individuals compared to live vaccines.
In conclusion, while killed vaccines are safe and effective, their major limitation is that they often do not trigger a strong or long-lasting immune response without the help of booster doses.