There are several misconceptions about AIRE enrollment and subsequent access to medical care in Italy. Generally speaking, once an Italian citizen is enrolled in AIRE, his contract with the ASL is terminated, and he no longer has access to his doctor, no access to subsidized medications, and so on. However, upon returning to Italy and for a period not exceeding 90 days, the Italian citizen continues to have access to emergency medical care and emergency hospitalization.
What happens if you return temporarily for more than 90 days? You can temporarily register with your local health authority (ASL) and gain access to their normal services, but you will need to provide appropriate documentation that you have returned to Italy for work, study or health reasons and NOT for vacations as this will not entitle you to temporary registration. It is good to remember that when you return permanently to Italy and then register your residence there, you will again have immediate access to all local health services.
In other words, the law assumes that an Italian citizen, once resident elsewhere, has access to the resources that are available in those countries, thus ceasing to use those services provided by public finances in Italy.
What if there are specific agreements between the country in which I reside abroad and Italy? It is here that the field becomes more complicated since, just as in the case of pensions, there are numerous bilateral agreements, in addition to EU agreements, that regulate access to health care outside the country of birth. Therefore, it is always advisable to check the situation with the local consulate, as they will normally monitor these matters on behalf of the location in which they are based. It would be too lengthy and probably misleading, given the changes and so on, to enumerate these exceptions here.
In any case, when it comes to health, it is always good to be overly cautious, so in case of doubt and if you are traveling from the country of AIRE registration to Italy, for vacations, it is advisable to get some form of travel insurance.