Omicron creates greater immune response. | Europa Press

Spain's Public Health Commission has issued a recommendation that adults who have had Covid should wait up to five months from time of diagnosis for a booster jab.

This was agreed at a meeting of regional health authorities at which it was decided that the minimum period should be four weeks but that there is now also the recommendation to delay for up to five months.

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The new recommendation follows the commission having previously set the interval at four weeks, a period that has been widely criticised by immunologists. They consider this to be an "immunological absurdity" after such a recent infection. The ministry explains: "Current evidence shows that having a SARS-CoV-2 infection after having the full course of the first vaccination leads to the development of a more powerful and broader immune response in terms of neutralising other variants of the virus, compared to the immune response observed in people who have only suffered infection or who have only received two doses."

In addition, Omicron infections "increase the response of memory cells to viral antigens" compared to post-vaccination infections caused by the Delta variant. This implies an extension of immunity. The interval between the second and third dose should therefore be a minimum of 4 weeks, although it is advisable that this is after five months.