Donuel, where did you get the information that "Astra Zenica is only 10% effective for the elderly"? You sound as if you DO want to be the bearer of bad news- maybe make sure it's true before sharing?
A report in German newspapers claiming similar has been denied, and AZ say good antibody response has been seen in the elderly (very few elderly people were included in the initial trials).
From AstraZeneca denies report vaccine less effective in elderly: In a written response, AstraZeneca described the German media reports saying its COVID-19 vaccine was shown to have a very low efficacy in the elderly as "completely incorrect". It said Britain's Joint Committee on Vaccination and Immunisation supported the vaccine's use in the elderly. It also said that a strong immune responses to the vaccine had been shown in blood analysis of elderly trial participants.
Unpublished Phase III analyses suggest high efficacy [in the over 65s] Many of the Phase III trials have made a conscious effort to recruit older people, and interim analyses of the Pfizer and Moderna vaccine have led to press releases announcing high degrees of efficacy.