The lynch mob attacks began in mid-September in a country that is one of the world's poorest and where belief in witchcraft is widespread.
Six people had already died in the attacks.
In Blantyre on Thursday, mobs "torched a 22-year-old epileptic man in Chileka, and another man was stoned to death ...after being suspected of being a blood sucker," said Ramsy Mushani, a national police spokesman.
A Reuters reporter witnessed the first incident at a police checkpoint on a road leading to the city's airport. A family member confirmed the man was epileptic and that he was killed while walking home from a nearby hospital.
Malawian President Peter Mutharika has been visiting parts of the country affected by the vampire scare, trying to prevent the deaths of innocent people.
The United Nations and US embassy have blacklisted several districts in Malawi as dangerous zones for staffers and nationals.