Natural membrane condoms made from animal tissue have 1,500 nm diameter pores which, in spite of not allowing sperm to pass, have a greater diameter than HIV and HBV, thereby allowing sexuallytransmitted viral diseases to become acquired 20.
En este estudio hay un riesgo incierto de sesgos ya que no se aclara el método de asignación aleatoria a las comunidades, como tampoco si hubo ocultamiento.