Question:
Who was the chair of USSR Ministry of Health in Oct, 1990?

Context:
 Mariya Kovrigina is the chair of USSR Ministry of Health from Mar, 1954 to Jan, 1959. 
 Yefim Smirnov is the chair of USSR Ministry of Health from Feb, 1947 to Dec, 1952. 
 Sergey Burenkov is the chair of USSR Ministry of Health from Dec, 1980 to Dec, 1986. 
 George Miterev is the chair of USSR Ministry of Health from Mar, 1946 to Feb, 1947. 
 Sergei Kurashov is the chair of USSR Ministry of Health from Jan, 1959 to Aug, 1965. 
 Yevgeniy Chazov is the chair of USSR Ministry of Health from Feb, 1987 to Mar, 1990. 
 Igor Denisov is the chair of USSR Ministry of Health from Apr, 1990 to Nov, 1991. 
 Boris Petrovsky is the chair of USSR Ministry of Health from Sep, 1965 to Dec, 1980.

Answer:
Igor Denisov