Measles vaccines protect you for a lifetime,
tetanus gives you about 10 years of cover
while flu vaccines need updating every year.
So why do some vaccines protect you much ?
Vaccines train your immune system to recognize a specific threat such as a,
virus and produce the right weapons to fight it off
including boosting proteins called antibodies.
The vaccine against measles provides lifelong protection partly
because the virus is quite stable and doesn’t really mutate
so once your body is familiar with it it will be easy to recognize.
A vaccine will train your immune system to recognize one strain,
but it may not be very good at protecting you
by the next winter when the virus could look very different.
Your immune system produces to fight off invaders,
while virus fighting antibodies may
fade relatively quickly they can leave behind.
Experts think the virus that causes
covid falls somewhere, in between
it has mutated fast enough to escape some of the protection provided by the
first round of vaccines.
Which were based on an earlier covid strain
but the immune system can still
recognize it enough to block a lot of
infections and to protect most people from different covid variant.
Experts say covid will probably remain a common infection
that continues to circulate so the hope is with vaccines making the virus less risky,
you can be exposed to it again and again
topping up your antibodies and strengthening your defenses for the next time.