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Summary: Background. International guidelines suggested skin tests with Polyethylene-glycol (PEG) and polysorbate 80 (PS-80), to investigate a possible hypersensitivity to these excipients either to identify subjects at risk of developing allergic reactions to Covid-19 vaccines, or in patients with suspected IgE mediated hypersensitivity reactions (HR) to the Covid-19 vaccine. The main purpose of this study was to investigate the prevalence of PEG and PS sensitization in patients with a clinical history of HR to drugs containing PEG/PS and in patients with a suspected Covid-19 vaccine immediate HR. Methods. This was a multicenter retrospective study conducted by allergists belonging to 20 Italian medical centers. Skin testing was performed in 531 patients with either a clinical history of suspected hypersensitivity reaction (HR) to drugs containing PEG and/or PS-80 (group 1:362 patient) or a suspected HR to Covid-19 vaccines (group 2: 169 patient), as suggested by the AAIITO/SIAAIC guidelines for the "management of patients at risk of allergic reactions to Covid-19 vaccines" [1]. Results. 10/362 (0.02%) had positive skin test to one or both excipients in group 1, 12/169 (7.1%) in group 2 (p less than 0.01). In group 2 HRs to Covid-19 vaccines were immediate in 10/12 of cases and anaphylaxis occurred in 4/12 of patients. Conclusions. The positivity of skin test with PEG and or PS before vaccination is extremely rare and mostly replaceable by an accurate clinical history. Sensitization to PEG and PS has to be investigated in patients with a previous immediate HR to a Covid-19 vaccine, in particular in patients with anaphylaxis.

For a number of years the measles vaccine has been tabled to be included among the compulsory vaccines with the not impossible aim of wiping out this disease. In practice, however, there have been isolated attempts to impose mass vaccination but, given that it is not compulsory, there has been a certain degree of resistance to the vaccine. In an attempt to interpret the reasons for this resistance we have identified three main causes: cultural heritage by family doctors and sometimes pediatricians ("a disease which is important to have had"). Limited information with underestimation of damaging effects of disease overemphasis of side-effects of vaccine and, among these, in particular fever which 30-35% of vaccinated children present between day 8-10, and the possible allergic reaction (chicken embryos-antibiotics). Using the latter as a starting point, we assessed the efficacy and tolerability of the Moraten Berna vaccine on 165 children aged between 10 months and 8 years. This vaccine is prepared using the Edmonston Zagreb strain cultured in diploid human cells, and does not therefore contain heterologous proteins, seroconversion was assessed in 54 of the vaccinated children (aged 10 months--3 years) by blood sample collected following an interval of between 40 and 120 days after vaccination. Anti-measles antibody titering was assayed using a neutralisation test on plates of cellular monostrate by assessing the titer (starting dilution of serum in test: 1:8). Seroconversion, as shown in table I, was obtained for all vaccinated subjects who presented a mean antibody titer of 916 mUI/ml.(ABSTRACT TRUNCATED AT 250 WORDS)