<70% effectiveness is...not so great to say the least when you have vaccines from BioNTech and Moderna at 95% effectiveness already.
"However, unpublished data suggests that leaving a longer gap between the first and second doses increases the overall effectiveness of the jab."
That may well help too. But at the end of the day, the world needs a lot of vaccine. It's better to have Pfizer/Moderna and the Oxford vaccine at our disposal, particularly when the latter is also much cheaper and easier to store (this will be crucial in developing countries and/or rural populations). What matters is having fewer people get sick or die, not ensuring everyone is given the vaccine with the greatest efficacy.
* Cost of vaccine
* Ease of manufacturing
* Ease of distribution
* Prevention of severe cases and hospitalisations
It seems all vaccines currently approved so far prevent hospitalisations completely. It won’t stop the epidemic completely depending on coverage but it’s enough to stop killing people.
But when I see '<70%' effectiveness compared to 95% effectiveness with the Pfizer-BioNTech and Moderna vaccines, the Oxford-AstraZeneca vaccine looks very disappointing and far from the top standard I have expected.
That is not good enough.
Hell, it's even more complex than that, because even given a type of vaccine, even subtle stuff such as dose size and time between the two doses seem to play a huge role, and this is again something that needs to be tweaked over time, using long phase 3 trials. I would attribute it much more to luck than actual skills here.
The sample size of Astrazeneca is much bigger as well.
With Moderna one, some people are loosing antibodies with in weeks.
That's... how vaccines work? Your anti-bodies don't stick around forever, and they're not supposed to. The purpose of the vaccine is to prime your memory B/T cells so that when the actual virus is introduced to your body the antibodies are produced much more rapidly, enough to kill the virus before it can take hold.