Artikel 31

1. Invasive medical examination, vaccination or other prophylaxis shall not be required as a condition of entry of any traveller to the territory of a State Party, except that, subject to Articles 32, 42 and 45, these Regulations do not preclude States Parties from requiring medical examination, vaccination or other prophylaxis or proof of vaccination or other prophylaxis:
a) when necessary to determine whether a public health risk exists;
b) as a condition of entry for any travellers seeking temporary or permanent residence;
c) as a condition of entry for any travellers pursuant to Article 43 or Annexes 6 and 7; or
d) which may be carried out pursuant to Article 23.
2. If a traveller for whom a State Party may require a medical examination, vaccination or other prophylaxis under paragraph 1 of this Article fails to consent to any such measure, or refuses to provide the information or the documents referred to in paragraph 1(a) of Article 23, the State Party concerned may, subject to Articles 32, 42 and 45, deny entry to that traveller. If there is evidence of an imminent public health risk, the State Party may, in accordance with its national law and to the extent necessary to control such a risk, compel the traveller to undergo or advise the traveller, pursuant to paragraph 3 of Article 23, to undergo:
a) the least invasive and intrusive medical examination that would achieve the public health objective;
b) vaccination or other prophylaxis; or
c) additional established health measures that prevent or control the spread of disease, including isolation, quarantine or placing the traveller under public health observation.