LONDON (Reuters) - The government will have to consider strengthening the three-tier system of restrictions used to control the spread of COVID-19 when the full lockdown in England ends, a medical adviser said on Monday. “We see very little effect from tier one. And I think when we look at what tiers may be there in the future, we will have to think about strengthening them in order to get us through the winter months until the vaccine’s available for everyone,” Susan Hopkins, from Public Health England, told a news conference. “We expect if the lockdown is working, and we’re all doing the best we can to have reduced or no social contact with other people that we will start to see cases decline over the next week.